electromagnets experiment

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How to Make an Electromagnet

Electromagnets are fascinating devices that have a wide range of applications in everyday life, from electric motors to MRI machines. Unlike permanent magnets, which are always magnetic, electromagnets turn on and off with the flow of electric current. Here are instructions for making two types of simple electromagnets, an explanation of how they work, and suggestions for experiments you can perform.

What Is an Electromagnet?

An electromagnet is a type of magnet in which the magnetic field is produced by an electric current. The simplest form of an electromagnet is a coil of wire, known as a solenoid, which generates a magnetic field when an electric current passes through it. By wrapping the wire around a ferromagnetic or ferrimagnetic material, such as iron, you can create a much stronger magnetic field.

How an Electromagnet Works

When an electric current flows through a wire, it generates a magnetic field around the wire. Even though electricity and magnetism seem like separate things, the basic concept is that electric and magnetic fields go together, forming an electromagnetic field. By coiling the wire, the magnetic fields from each loop of the wire combine and produce a stronger field. Inserting a ferromagnetic or ferrimagnetic core (e.g., an iron nail) inside the coil amplifies the magnetic field because these materials have high magnetic permeability. This means they enhance and concentrate the magnetic field created by the coil.

Uses of Electromagnets

Electromagnets have numerous applications, including:

• Speakers : Electromagnets convert electrical signals into sound. The varying electrical current in the electromagnet interacts with a permanent magnet, making the speaker diaphragm move and produce sound waves.
• Electric motors and generators : Household appliances such as fans, washing machines, refrigerators, and power tools use electric motors that rely on electromagnets for converting electrical energy into mechanical motion.
• Transformers : Transformers use electromagnets to change the voltage of alternating current (AC) electricity. This allows for efficient transmission of electricity over long distances and the safe delivery of power to homes and businesses.
• Relays and solenoids : Relays and switches use electromagnets for opening and closing circuits.
• Magnetic locks and lifting equipment : Applying current to an electromagnet creates a magnetic field that holds a door closed or an item in place.
• Medical devices like MRI machines : Powerful electromagnets interact with hydrogen atoms in the body to create detailed images.

Project Instructions: Basic Electromagnet

All you need is a battery (or other power source) and some wire for making a basic electromagnet.

• Insulated copper wire (approximately 1 meter)
• Small piece of sandpaper
• Paper clips or small metal objects for testing

Instructions:

• Strip about 2 cm of insulation off each end of the wire using the sandpaper.
• Coil the wire tightly around a cylindrical object like a pencil to create a solenoid. Leave about 10 cm of wire free at each end.
• Remove the coil from the pencil.
• Attach one end of the wire to the positive terminal of the AA battery using tape.
• Attach the other end of the wire to the negative terminal of the battery using tape.
• Test the electromagnet by bringing it close to paper clips or small metal objects. The coil attracts them when the battery is connected.

Project Instructions: Electromagnet with a Core

Adding a core to the solenoid greatly enhances the power of the electromagnet.

• Iron nail or iron rod (about 10 cm long)
• Coil the wire tightly around the iron nail or rod, leaving about 10 cm of wire free at each end.
• Test the electromagnet by bringing it close to paper clips or small metal objects. The coil attract more objects or attract them more strongly than the basic electromagnet.

Proving Increased Strength:

• Compare the number of paper clips attracted by the basic electromagnet and the core-enhanced electromagnet.
• Compare the maximum distance for attracting paper clips by the basic electromagnet and the core-enhanced electromagnet.

How to Make an Electromagnet Stronger

There are multiple ways of increasing the strength of an electromagnet:

• Increase the number of coils: More coils of wire result in a stronger magnetic field.
• Use a stronger battery: Higher voltage increases the current and thus the magnetic field.
• Use a thicker wire: This reduces resistance, allowing more current flow.
• Improve the core material: Use materials with higher magnetic permeability, like iron or steel.
• Cool the wire: Reducing temperature decreases resistance, allowing more current flow.

Experiment Suggestions

Turn the electromagnet science project into an experiment . Predict the outcome of making a change and then test it (conduct an experiment) and reach a conclusion:

• Use different materials (iron, steel, aluminum) as cores and compare their magnetic strengths. Can you tell which metals are magnetic and which are not?
• Create electromagnets with different numbers of wire coils and measure the difference in strength.
• Use batteries of different voltages and observe the effect on the magnetic strength.
• Measure how far the electromagnet attracts paper clips and test how this changes with different configurations.
• Test the electromagnet’s strength at different temperatures to see how resistance affects the current and magnetic field.
• Dawes, Chester L. (1967). “Electrical Engineering”. In Baumeister, Theodore (ed.). Standard Handbook for Mechanical Engineers (7th ed.). McGraw-Hill.
• Gates, Earl (2013). Introduction to Basic Electricity and Electronics Technology . Cengage Learning. ISBN 978-1133948513.
• Sturgeon, W. (1825). “Improved Electro Magnetic Apparatus”. Trans. Royal Society of Arts, Manufactures, & Commerc e. 43: 37–52. in Miller, T.J.E (2001). Electronic Control of Switched Reluctance Machines . Elsevier Science. ISBN 978-0-7506-5073-1.

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Science Projects > Physics & Engineering Projects > Electromagnetism Experiments  

Electromagnetism Experiments

Electric current flowing through a wire creates a magnetic field that attracts ferromagnetic objects, such as iron or steel. This is the principle behind electromagnets and magnetic levitation trains. It allows cranes to pick up whole cars in the junkyard and makes your doorbell ring. You can read about it here , and then watch it work when you do these experiments. (Adult supervision recommended.)

Electromagnetic Experiments

-Electromagnetic Suction -Electromagnet -Magnetic Propulsion

Experiment 1: Electromagnetic Suction

A single strand of wire produces only a very weak magnetic field, but a tight coil of wire (called a solenoid ) gives off a stronger field. In this experiment, you will use an electric current running through a solenoid to suck a needle into a straw!

What You Need:

• drinking straw
• 5 feet insulated copper wire
• 6-volt battery

What You Do:

1. Make your solenoid. Take five feet of insulated copper wire and wrap it tightly around the straw. Your solenoid should be about 3 inches long, so you’ll have enough wire to wrap a couple of layers.

2. Trim the ends of the straw so they just stick out of the solenoid.

3. Hold the solenoid horizontally and put the end of the needle in the straw and let go. What happens?

4. Now strip an inch of insulation off each end of the wire and connect the ends to the 6-volt battery. Insert the needle part-way in the straw again and let go. This time what happens? (Don’t leave the wire hooked up to the battery for more than a few seconds at a time – it will get hot and drain the battery very quickly)

When you hooked your solenoid up to a battery, an electric current flowed through the coils of the wire, which created a magnetic field. This field attracted the needle just like a magnet and sucked it into the straw. Try some more experiments with your solenoid – will more coils make it suck the needle in faster? Will it still work with just a few coils? Make a prediction and then try it out!

Experiment 2: Electromagnet

As you saw in the last experiment, electric current flowing through a wire produces a magnetic field. This principle comes in very handy in the form of an electromagnet. An electromagnet is wire that is tightly wrapped around a ferromagnetic core. When the wire is connected to a battery, it produces a magnetic field that magnetizes the core. The magnetic fields of the core and the solenoid work together to make a very strong magnet. The best part about it is that the magnetic force stops when the electricity is turned off! Try it yourself with this experiment:

• large iron nail

1. Tightly wrap the wire around the nail to make a solenoid with a ferromagnetic core. If you have enough wire, wrap more than one layer. (If your nail fits inside the straw from the last experiment, you can use that solenoid instead of rewrapping the wire.)

2. Try to pick up some paperclips with the wire-wrapped nail. Can you do it?

3. Strip an inch of insulation off each end of the wire.

4. Hook up the wire to the battery and try again to pick up the paperclips with the nail. This time the electricity will create a magnetic field and the nail will attract paperclips! (Don’t leave the wire hooked up to the battery for more than a few seconds at a time – it will get hot and drain the battery very quickly.)

Experiment some more with your electromagnet. Count how many paperclips it can pick up. If you coil more wire around it will it pick up more paperclips? How many paperclips can you pick up if you only use half as much wire? What would happen if you used a smaller battery, like a D-size? Predict what you think will happen and then try it out!

Experiment 3: Magnetic Propulsion

A maglev (magnetically levitated) train doesn’t use a regular engine like a normal train. Instead, electromagnets in the track produce a magnetic force that pushes the train from behind and pulls it from the front. You can get an idea of how it works using some permanent magnets and a toy car.

• 3 bar magnets

1. Tape a bar magnet to a small toy car with the north pole at the back of the car and the south pole at the front.

2. Put the car on a hard surface, like a linoleum floor or a table. Hold a bar magnet behind the car with the south pole facing the car. As you move it near the car, what happens? The south pole of your magnet repels the north pole of the magnet on the car, making the car move forward.

3. Have someone else hold another magnet in front of the car, with the north pole facing the car. Does the car move faster with one magnet ‘pushing’ from behind and the other magnet ‘pulling’ from ahead?

In our example, the permanent magnets have to move with the car to keep it going. In a maglev track, though, the electromagnets just change their poles by changing the direction of the electric current. They stay in the same spot, but their poles change as the train goes by so it will always be repelled from the electromagnets behind it and attracted by the electromagnets in front of it!

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How to Make an Electromagnet - Learn how to use electricity to create a magnet

Posted by Admin / in Energy & Electricity Experiments

A cool science experiment which teaches kids about a magnetic field is to make an electromagnet from scratch. Electromagnet principles and theory was developed by Andre Marie Ampere in 1821. D.F. Arago then invented the first working electromagnet. This invention helped lead Michael Faraday to later invent the electric motor.

Materials Needed

• Magnet wire (about 5-10 feet)
• Metal paper clips
• Battery (D cell or lantern battery) with battery holder or connection wires

EXPERIMENT STEPS

Step 1: First, an iron or steel nail is needed. Do not use a galvanized or aluminum nail or the required magnetic field is not created. Leaving approximately 6" of wire slack, start wrapping the magnet wire around the iron nail.

Step 2: Wrap the wire 25 times around the nail.

Step 3: Attach both ends of the loose wire to the battery. Connect one side to the positive (+) side and the other side to the negative (-) side. Do not leave the wire attached to both battery terminals too long or the battery power will be drained and the wire will get hot.

Step 4: Move the nail near the paper clips.

Step 5: Disconnect one side of the wire from the battery.

Step 6: Wrap the wire another 25 turns around the nail.

Science Learned

The electromagnet proves that a magnetic field and electricity are related. In fact, calculation of electromotive force is very similar to Ohm's law. Remember that Ohm's law is used to calculate the voltage drop across a circuit with a resistor, where v=iR (voltage=current x resistance). To calulcate the electromotive force in a magnetic circuit use the equation F=IN (Force=current x number of turns). The number of turns and the current in the battery both change the amount of magnetic force in an electromagnet.

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NOTIFICATIONS

Making an electromagnet.

• + Create new collection

Magnetism and electricity are forces generated by the movement of electrons. They are both electromagnetic forces – the interplay of these two forces is the basis for many modern technologies. Electromagnets are magnets that are generated by electric fields. They have the advantage over regular magnets in that they can be switched on and off.

Electromagnets can be created by wrapping a wire around an iron nail and running current through the wire. The electric field in the wire coil creates a magnetic field around the nail. In some cases, the nail will remain magnetised even when removed from within the wire coil. Electromagnets are fundamental to many modern technologies.

In this activity, students build a simple electromagnet.

By the end of this activity, students should be able to:

• build a simple electromagnet
• explore the influence of different variables on the effectiveness of the electromagnet
• work methodically to adapt their design to improve the electromagnet function.

Download the Word file (see link below) for:

• background information for teachers
• student instructions.

Nature of science

The NZC ‘Investigating in science’ strand of the nature of science requires teachers to provide students with opportunities to extend their experiences and personal explanations of the natural world through exploration, play, asking questions and discussing simple models. This activity provides such opportunities.

Activity ideas

Other activities on the SLH that explore magnetism include Probing fridge magnets , Make an electric motor , Investigating magnetism and Making a weather vane and compass .

Related content

There are several articles and a PLD session related to magnetism. They include Introducing magnetism , Using magnetism , Geothermal power , Superconductivity , Magnetic resonance imaging (MRI) and Exploring magnetism .

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• Intro Lab - Build an Electromagnet

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Basic Projects and Test Equipment

• Intro Lab - How to Use a Voltmeter to Measure Voltage
• Intro Lab - How to Use an Ohmmeter to Measure Resistance
• Intro Lab - How to Use an Ammeter to Measure Current
• Intro Lab - Ohm’s Law
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• Intro Lab - A Simple Lighting Circuit
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• Intro Lab - Circuit With a Switch
• Intro Lab - Electromagnetic Induction

In this hands-on electronics experiment, you will build an electromagnet and learn about electromagnetism including the relationship of magnetic polarity to current flow.

Project overview.

In this project, you will build and test the electromagnet circuit illustrated in Figure 1.  Electromagnetism has many applications, including:

• Electric motors
• Computer printer mechanisms
• Magnetic media write heads (tape recorders and disk drives)

Figure 1. Electromagnet circuit for generating a magnetic field from an electric current.

Parts and materials.

• 6 V battery
• Magnetic compass
• Small permanent magnet
• Spool of 28-gauge magnet wire
• Large bolt, nail, or steel rod
• Electrical tape

Magnet wire is a term for thin-gauge copper wire with enamel insulation instead of rubber or plastic insulation. Its small size and very thin insulation allow for many turns to be wound in a compact coil. Keep in mind that you will need enough magnet wire to wrap hundreds of turns around the bolt, nail, or other rod-shaped steel forms.

Another thing, make sure to select a bolt, nail, or rod that is magnetic. Stainless steel, for example, is non-magnetic and will not function for the purpose of an electromagnet coil! The ideal material for this experiment is soft iron, but any commonly available steel will suffice.

Learning Objectives

• Application of the left-hand rule
• Electromagnet construction

Instructions

Step 1:  Wrap a single layer of electrical tape around the steel bar (or bolt or mail) to protect the wire from abrasion.

Step 2:  Proceed to wrap several hundred turns of wire around the steel bar, making the coil as even as possible. It is okay to overlap wire, and it is okay to wrap in the same style that a fishing reel wraps the line around the spool. The only rule you must follow is that all turns must be wrapped around the bar in the same direction (no reversing from clockwise to counter-clockwise!).

I find that a drill press works as a great tool for coil winding: clamp the rod in the drill’s chuck as if it were a drill bit, then turn the drill motor on at a slow speed and let it do the wrapping! This allows you to feed wire onto the rod in a very steady, even manner.

Step 3:  After you’ve wrapped several hundred turns of wire around the rod, wrap a layer or two of electrical tape over the wire coil to secure the wire in place.

Step 4:  Scrape the enamel insulation off the ends of the coil wires to expose the wire for connection to jumper leads

Step 5: Connect the coil to a battery, as illustrated in Figure 1 and defined in the circuit schematic of Figure 2.

Figure 2.  Schematic diagram of the electromagnet circuit.

Step 6:  When the electric current goes through the coil, it will produce a strong magnetic field with one pole at each end of the rod. This phenomenon is known as electromagnetism. With the electromagnet energized (connected to the battery), use the magnetic compass to identify the north and south poles of the electromagnet. 

Step 7: Place a permanent magnet near one pole and note whether there is an attractive or repulsive force.

Step 8:  Reverse the orientation of the permanent magnet and repeat steps 7 and 8. Note the difference in force caused by changing the polarity of the applied voltage and the direction of the current flow. 

Inductive Kickback

You might notice a significant spark whenever the battery is disconnected from the electromagnet coil, much greater than the spark produced if the battery is short-circuited. This spark results from a high-voltage surge created whenever current is suddenly interrupted through the coil.

The effect is called inductive kickback  and can deliver a small but harmless electric shock. To avoid receiving this shock, do not place your body across the break in the circuit when de-energizing. Use one hand at a time when un-powering the coil, and you’ll be perfectly safe.

Related Content

Learn more about the fundamentals behind this project in the resources below.

• Magnetism and Electromagnetism
• Electromagnetism

Worksheets:

• Basic Electromagnetism and Electromagnetic Induction Worksheet
• Intermediate Electromagnetism and Electromagnetic Induction Worksheet
• Advanced Electromagnetism and Electromagnetic Induction Worksheet
• Textbook Index

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FREE K-12 standards-aligned STEM

curriculum for educators everywhere!

Find more at TeachEngineering.org .

• TeachEngineering
• Creating an Electromagnet

Hands-on Activity Creating an Electromagnet

Grade Level: 4 (3-5)

Time Required: 45 minutes

Expendable Cost/Group: US $2.00

Group Size: 2

Activity Dependency: None

Associated Informal Learning Activity: Creating an Electromagnet!

Subject Areas: Physical Science, Physics

NGSS Performance Expectations:

Activities Associated with this Lesson Units serve as guides to a particular content or subject area. Nested under units are lessons (in purple) and hands-on activities (in blue). Note that not all lessons and activities will exist under a unit, and instead may exist as "standalone" curriculum.

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Engineering connection, learning objectives, materials list, worksheets and attachments, more curriculum like this, pre-req knowledge, introduction/motivation, vocabulary/definitions, troubleshooting tips, activity extensions, activity scaling, user comments & tips.

Engineers design electromagnets, which are a basic part of motors. Electromagnetic motors are a big part of everyday life, as well as industries and factories. We may not even realize that we interact with electromagnets on a daily basis as we use a wide variety of motors to make our lives easier. Common devices that use electromagnetic motors are: refrigerators, clothes dryers, washing machines, dishwashers, vacuum cleaners, sewing machines, garbage disposals, doorbells, computers, computer printers, clocks, fans, car starters, windshield wiper motors, electric toothbrushes, electric razors, can openers, speakers, music or tape players, etc.

After this activity, students should be able to:

• Relate that electric current creates a magnetic field.
• Describe how an electromagnet is made.
• Investigate ways to change the strength of an electromagnet.
• List several items that engineers have designed using electromagnets.

Educational Standards Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards. All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN) , a project of D2L (www.achievementstandards.org). In the ASN, standards are hierarchically structured: first by source; e.g. , by state; within source by type; e.g. , science or mathematics; within type by subtype, then by grade, etc .

Ngss: next generation science standards - science.

Common Core State Standards - Math

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International Technology and Engineering Educators Association - Technology

State standards, colorado - math, colorado - science.

Each group needs:

• nail, 3-inch (7.6 cm) or longer (made of zinc, iron or steel, but not aluminum)
• 2 feet (.6 m) insulated copper wire (at least AWG 22 or higher)
• D-cell battery
• several metal paperclips, tacks or pins
• wide rubber band
• Building an Electromagnet Worksheet

For each electromagnetic field station:

• cardboard toilet paper tube
• insulated copper wire (at least AWG 22 or higher), several feet (1 m)
• cardboard (~ 5 x 5 inches or 13 x 13 cm)
• clothespins or clamps (optional)
• masking tape
• rubber band
• 2-3 D-cell batteries
• 9-V (volt) battery
• several metal paperclips, tacks and/or pins
• extra batteries, if available: 6-V, 12-V, lantern batteries
• (optional) electrical tape
• 2 small orienteering compasses

For the entire class to share:

• wire cutters
• wire strippers

Some knowledge of magnetic forces (poles, attraction forces). Refer to the Magnetism unit, Lesson 2: Two Sides of One Force , for this information on electromagnets.

Today, we are going to talk about electromagnets and create our own electromagnets! First, can anyone tell me what an electromagnet is? (Listen to student ideas.) Well, an electromagnet's name helps tell us what it is. (Write the word electromagnet on the classroom board for students to see.) Let's break it down. The first part of the word,  electro , sounds like electricity. The second part of the word, magnet , is what it sounds like—a magnet! So, an electromagnet is a magnet that is created by electricity.

The really important thing to remember today is that electricity can create a magnetic field. This may sound strange, because we're used to magnetic fields just coming from magnets, but it is really true! A wire that has electrical  current running through it creates a magnetic field. In fact, the simplest electromagnet is a single wire that is coiled up and has an electric current running through it. The magnetic field generated by the coil of wire is like a regular bar magnet. If we put an iron (or nickel, cobalt, etc.) rod (perhaps a nail) through the center of the coil (see Figure 1), the rod becomes the magnet, creating a magnetic field. Where do we find the electricity for an electromagnet? Well, we can get this electricity a few ways, such as from a battery or a wall outlet.

We can make this magnetic field stronger by increasing the amount of electric current going through the wire or we can increase the number of wire wraps in the coil of the electromagnet. What do you think happens if we do both of these things? That's right! Our magnet will be even stronger!

Engineers use electromagnets when they design and build motors . Motors are in use around us everyday, so we interact with electromagnets all the time without even realizing it! Can you think of some motors that you have used? (Possible answers: Washing machine, dishwasher, can opener, garbage disposal, sewing machine, computer printer, vacuum cleaner, electric toothbrush, compact disc [CD] player, digital video disc [DVD] player, VCR tape player, computer, electric razor, an electric toy [radio-controlled vehicles, moving dolls], etc.)

Before the Activity

• Gather materials and make copies of the Building an Electromagnet Worksheet .
• Set up enough Electromagnetic Field Stations to accommodate teams of two students each.
• As an alternative, conduct both parts of the activity as teacher-led class demonstrations.

• Prepare for Electromagnetic Field Stations: Wrap wire around a cardboard toilet paper tube 12-15 times to make a wire loop. Leave two long tails of wire hanging from the coil. Poke four holes in the cardboard. Weave the wire ends through the cardboard holes so that the card board tube and coil are attached to the cardboard (see Figure 2). Use clothespins, clamps or tape to secure the cardboard to a table or desk. Using masking tape or rubber band, connect one end of the coil wire to any battery, leaving the other end of the wire not connected to the battery. Place some pins, paperclips or tacks at the station. Also, place any other available extra batteries (6V, 12V, etc.) and two, small orienteering compasses at this station.
• Prepare for Building an Electromagnet: For this portion of the activity, either set up the materials at a station, or give them to pairs of students to work on at their desks.
• Set aside a few extra batteries for students to test their own electromagnets. These might include the 9-V batteries. You can make a 3-V battery setup by connecting 2 D-cells in series or a 4.5-V battery setup by connecting 3 D-cells in series.
• Cut one 2-ft (.6 m) piece of wire for each team. Using wire strippers, remove about ½ inch (1.3 cm) of insulation from both ends of each piece of wire.

With the Students: Electromagnetic Field Stations

• Divide the class into pairs of students. Hand out one worksheet per team.
• Working from the pre-activity setup (see Figure 2), in which one end of the coiled wire is attached to one end of the battery, have students connect the other end of the wire to the other end of the battery using tape or rubber band.
• To locate the magnetic field of the electromagnet, direct students to move the compass in a circle around the electromagnet, paying attention to the direction that the compass points (see Figure 3). Direct students to draw the battery, coil and magnetic field on their worksheets. Use arrows to show the magnetic field. Label the positive and negative ends of the battery and the poles of the magnetic field. What happens if you dangle a paperclip from another paperclip near the coil (see Figure 3)? (Answer: The dangling paperclip moves, changes direction and/or wobbles.)

• Next, reverse the connection of the electromagnet by changing both ends of the wire to the opposite ends of the battery. (When the direction of current is reversed in either a coil or electromagnet, the magnetic poles reverse—the north pole becomes the south pole, and the south pole becomes the north pole.) Use the compass to check the direction of the magnetic field. Make a second drawing. Dangle the paperclip near the coil again. What happens? (Answer: Again, the dangling paperclip moves, changes direction and/or wobbles.)
• Remove at least one end of the wire from the battery to conserve battery power.
• If time permits, use different batteries and observe any changes. A higher voltage translates to a greater current, and with more current, the electromagnet becomes stronger.

With the Students: Building an Electromagnet

• Make sure each student pair has the following materials: 1 nail, 2 feet (.6 m) of insulated wire, 1 D-cell battery, several paperclips (or tacks or pins) and a rubber band.
• Wrap the wire around a nail at least 20 times (see Figure 4). Ensure students wrap their nails tightly, leaving no gaps between the wires and not overlapping the wraps.
• Give the students several minutes to see if they can create an electromagnet on their own before giving them the rest of the instructions.
• To continue making the electromagnet, connect the ends of the coiled wire to each end of the battery using the rubber band to hold the wires in place (see Figure 4).

• Test the strength of the electromagnet by seeing how many paperclips it can pick up.
• Record the number of paperclips on the worksheet.
• Disconnect the wire from the battery after testing the electromagnet. Can the electromagnet pick up paperclips when the current is disconnected? (Answer: No)
• Test how varying the design of the electromagnet affects its strength. The two variables to modify are the number of coils around the nail and the current in the coiled wire by using a different size or number of batteries. To conserve the battery's power, remember to disconnect the wire from the battery after each test.
• Complete the worksheet; making a list of ways engineers might be able to use electromagnets.
• Conclude by holding a class discussion. Compare results among teams. Ask students the post-assessment engineering discussion questions provided in the Assessment section.

battery: A cell that carries a charge that can power an electric current.

current: A flow of electrons.

electromagnet: A magnet made of an insulated wire coiled around an iron core (or any magnetic material such as iron, steel, nickel, cobalt) with electric current flowing through it to produce magnetism. The electric current magnetizes the core material.

electromagnetism: Magnetism created by an electric current.

engineer: A person who applies her/his understanding of science and mathematics to create things for the benefit of humanity and our planet. This includes the design, manufacture and operation of efficient and economical structures, machines, products, processes and systems.

magnet: An object that generates a magnetic field.

magnetic field: The space around a magnet in which the magnet's magnetic force is present.

motor: An electrical device that converts electrical energy into mechanical energy.

permanent magnet: An object that generates a magnetic field on its own (without the help of a current).

solenoid: A coil of wire.

Pre-Activity Assessment

Prediction : Ask students to predict what will happen when a wire is wrapped around a nail and electricity is added. Record their predictions on the classroom board.

Brainstorming : In small groups, have students engage in open discussion. Remind them that no idea or suggestion is "silly." All ideas should be respectfully heard. Ask the students: What is an electromagnet?

Activity-Embedded Assessment

Worksheet : At the beginning of the activity, hand out the Building an Electromagnet Worksheet . Have students make drawings, record measurements and follow along with the activity on their worksheets. After students finish the worksheet, have them compare answers with a peer or another pair, giving all students time to finish. Review their answers to gauge their mastery of the subject.

Hypothesize : As students make their electromagnet, ask each group what would happen if they changed the size of their battery. How about more coils of wire around the nail? (Answer: An electromagnet can be made stronger in two ways: increasing the amount of electric current going through the wire or increasing the number of wire wraps in the coil of the electromagnet.)

Post-Activity Assessment

Engineering Discussion Questions : Solicit, integrate and summarize student responses.

• What are ways an engineer might modify an electromagnet to change the strength of its magnetic field? Which modifications might be the easiest or cheapest? (Possible answers: Increasing the number of coils used in the solenoid [electromagnet] is probably the least expensive and easiest way to increase the strength of an electromagnet. Or, an engineer might increase the current in the electromagnet. Or, an engineer might use a metal core that is more easily magnetized.)
• How might engineers use electromagnets in separating recyclable materials? (Answer: Some of the metals in a salvage or recycling pile are attracted to a magnet and can be easily separated. Non-ferrous metals must go through a two-step process in which a voltage is applied to the metal to temporarily induce a current in it, which temporarily magnetizes the metal so it is attracted to the electromagnet for separation from non-metals.)
• What are some ways that engineers might be able to use electromagnets? (Possible answers: Engineers use electromagnets in the design of motors. For examples, see the possible answers to the next question.)
• How are electromagnets used in everyday applications? (Possible answers: Motors are in use around us everyday, for example, refrigerator, washing machine, dishwasher, can opener, garbage disposal, sewing machine, computer printer, vacuum cleaner, electric toothbrush, compact disc [CD] player, digital video disc [DVD] player, VCR tape player, computer, electric razor, an electric toy [radio-controlled vehicles, moving dolls], etc.)

Graphing Practice : Present the class with the following problems and ask students to graph their results (or the entire class' results). Discuss which variables made a bigger change in the strength of the electromagnet.

• Make a graph that shows how the electromagnet strength changed as you changed the number of wire coils in your electromagnet.
• Make a graph that shows how the strength of your electromagnet changed as the current changed (as you changed the battery size).

Safety Issues

The electromagnet can get quite warm, particularly at the terminals, so have students disconnect their batteries at frequent intervals.

A high density of nail wraps is important to produce a magnetic field. If the wrapped nails are not acting as magnets, check students’ coil wraps to ensure they are not crisscrossed, and that the wraps are tight. Also, use thin gauge wire to enable more wraps along the length of the nail.

Iron nails work better than bolts since the bolt threads do not permit smooth wrapping of the copper wire, which may disrupt the magnetic field.

Avoid using batteries that are not fully charged. Partially discharged batteries will not generate a strong and observable magnetic reaction.

If the electromagnets get too warm, have students use rubber kitchen gloves to handle them.

Another way to vary the current in the electromagnet is to use wires of different gauges (thickness) or of different materials (for example: copper vs. aluminum). Ask students to test different wire types to see how this affects the electromagnet's strength. As a control, keep constant the number of coils and amount of current (battery) for all wire tests. Then, based on their rest results, ask students to make guesses about the resistances of the various wires.

• For lower grades, have students follow along with the teacher-led demonstration to create a simple electromagnet. Discuss the basic definition of an electromagnet and how electromagnets are used in everyday applications.
• For upper grades, have students investigate ways to change the strength of their electromagnets without giving them any hints or clues. Have students graph their worksheet data from varying the number of coils and/or battery size in their electromagnet.

Students learn more about magnetism, and how magnetism and electricity are related in electromagnets. They learn the fundamentals about how simple electric motors and electromagnets work. Students also learn about hybrid gasoline-electric cars and their advantages over conventional gasoline-only-pow...

Students are briefly introduced to Maxwell's equations and their significance to phenomena associated with electricity and magnetism. Basic concepts such as current, electricity and field lines are covered and reinforced. Through multiple topics and activities, students see how electricity and magne...

Students induce EMF in a coil of wire using magnetic fields. Students review the cross product with respect to magnetic force and introduce magnetic flux, Faraday's law of Induction, Lenz's law, eddy currents, motional EMF and Induced EMF.

Students investigate the properties of magnets and how engineers use magnets in technology. Specifically, students learn about magnetic memory storage, which is the reading and writing of data information using magnets, such as in computer hard drives, zip disks and flash drives.

Contributors

Supporting program, acknowledgements.

The contents of this digital library curriculum were developed under grants from the Fund for the Improvement of Postsecondary Education (FIPSE), U.S. Department of Education, and National Science Foundation (GK-12 grant no 0338326). However, these contents do not necessarily represent the policies of the Department of Education or National Science Foundation, and you should not assume endorsement by the federal government.

Last modified: July 30, 2020

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more in Experiments

Make an electromagnet, you will need.

A large iron nail (about 3 inches) About 3 feet of THIN COATED copper wire A fresh D size battery Some paper clips or other small magnetic objects

1. Leave about 8 inches of wire loose at one end and wrap most of the rest of the wire around the nail. Try not to overlap the wires. 2. Cut the wire (if needed) so that there is about another 8 inches loose at the other end too.

3. Now remove about an inch of the plastic coating from both ends of the wire and attach the one wire to one end of a battery and the other wire to the other end of the battery. See picture below. (It is best to tape the wires to the battery – be careful though, the wire could get very hot!) 4. Now you have an ELECTROMAGNET! Put the point of the nail near a few paper clips and it should pick them up! NOTE: Making an electromagnet uses up the battery somewhat quickly which is why the battery may get warm, so disconnect the wires when you are done exploring.

How does it work?

Most magnets, like the ones on many refrigerators, cannot be turned off, they are called permanent magnets. Magnets like the one you made that can be turned on and off, are called ELECTROMAGNETS. They run on electricity and are only magnetic when the electricity is flowing. The electricity flowing through the wire arranges the molecules in the nail so that they are attracted to certain metals. NEVER get the wires of the electromagnet near at household outlet! Be safe – have fun!

MAKE IT AN EXPERIMENT

The project above is a DEMONSTRATION. To make it a true experiment, you can try to answer these questions:

1. Does the number of times you wrap the wire around the nail affect the strength of the nail?

2. Does the thickness or length of the nail affect the electromagnets strength?

3. Does the thickness of the wire affect the power of the electromagnet?

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A robust tri-electromagnet-based 6-dof pose tracking system using an error-state kalman filter.

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Dong, S.; Wang, H. A Robust Tri-Electromagnet-Based 6-DoF Pose Tracking System Using an Error-State Kalman Filter. Sensors 2024 , 24 , 5956. https://doi.org/10.3390/s24185956

Dong S, Wang H. A Robust Tri-Electromagnet-Based 6-DoF Pose Tracking System Using an Error-State Kalman Filter. Sensors . 2024; 24(18):5956. https://doi.org/10.3390/s24185956

Dong, Shuda, and Heng Wang. 2024. "A Robust Tri-Electromagnet-Based 6-DoF Pose Tracking System Using an Error-State Kalman Filter" Sensors 24, no. 18: 5956. https://doi.org/10.3390/s24185956

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Title: electromagnetic normalization of channel matrix for holographic mimo communications.

Abstract: Holographic multiple-input and multiple-output (MIMO) communications introduce innovative antenna array configurations, such as dense arrays and volumetric arrays, which offer notable advantages over conventional planar arrays with half-wavelength element spacing. However, accurately assessing the performance of these new holographic MIMO systems necessitates careful consideration of channel matrix normalization, as it is influenced by array gain, which, in turn, depends on the array topology. Traditional normalization methods may be insufficient for assessing these advanced array topologies, potentially resulting in misleading or inaccurate evaluations. In this study, we propose electromagnetic normalization approaches for the channel matrix that accommodate arbitrary array topologies, drawing on the array gains from analytical, physical, and full-wave methods. Additionally, we introduce a normalization method for near-field MIMO channels based on a rigorous dyadic Green's function approach, which accounts for potential losses of gain at near field. Finally, we perform capacity analyses under quasi-static, ergodic, and near-field conditions, through adopting the proposed normalization techniques. Our findings indicate that channel matrix normalization should reflect the realized gains of the antenna array in target directions. Failing to accurately normalize the channel matrix can result in errors when evaluating the performance limits and benefits of unconventional holographic array topologies, potentially compromising the optimal design of holographic MIMO systems.

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USAID Quality Technologies Revitalizing Agriculture Activity (Q’tra) Signs 20 Co-Investment Agreements to Enhance Water Efficiency and Resilience in the West Bank

For Immediate Release

Press Release

Activity Launch and Grants Signing Ceremony in Jericho, West Bank on September 10, 2024

JERICHO, West Bank: Today in Jericho, the United States Agency for International Development (USAID), the mayor of Jericho Abdel Kareem Sider, and local farmers launched the Quality Technologies Revitalizing Agriculture Activity (Q’tra) by signing 20 new co-investment agreements. Totaling $1.3 million, the investments will provide farmers with water efficient irrigation equipment to improve water efficiency and resilience in the West Bank. The co-investment agreements will help about 300 farmers from Jericho and Tubas governorates adopt water-saving technologies, including low-flow emitters, automated irrigation systems, and pond linings. The activity will also provide electromagnetic ionizers and sand filters to enhance irrigation water quality.

Agricultural water consumes more than half of the West Bank’s limited freshwater resources, and agricultural practices, particularly irrigation practices, must be improved and modernized to improve agricultural water productivity and reduce stress on groundwater. Efforts through USAID’s Q’tra activity will work to enhance water efficiency and productivity, support agricultural resilience, and improve water and food security.

Q'tra is a 4-year, $36 million USAID-funded Activity designed to enhance water efficiency and promote climate-resilient agriculture. Q'tra will increase farmers’ access to advanced irrigation technologies that promote water savings, such as low-flow emitter drip systems, aiming to reduce water use by 4 million cubic meters in the West Bank and Gaza. Through targeted training, Q’tra will enable farmers to adopt improved resilient conservation practices and better manage freshwater resources and associated ecosystems through the elimination of chemical and fertilizer use.

Jericho Mayor Abdel Kareem Sider emphasized the significance of the Activity and stressed that the need to optimize water use and conserve resources has become increasingly critical.

”Q'tra will eventually provide advanced technologies and technical and training assistance for 11,500 Palestinian farmers. The activity will ensure inclusivity by offering opportunities to men, women, youth, and people with disabilities alike. By collaborating with local and international partners, Q'tra aims to maximize its impact and ensure efficient use of resources to benefit farmers, and their communities," stated Q'tra's Chief of Party, Jean Francois Guay.

USAID and Q'tra remain dedicated to advancing development goals and supporting communities in the West Bank and Gaza. The signing of these grant agreements underscores a continued commitment to building resilience and improving livelihoods and economic growth amidst current challenges.

About USAID:

The United States Agency for International Development (USAID) is the lead U.S. Government Agency that works to end extreme global poverty and enable resilient, democratic societies to realize their potential. In the West Bank and Gaza, USAID assistance aims to increase stability and improve lives of Palestinians by working within local communities to increase economic opportunity and access to basic services, promote effective governance, empower youth, and provide humanitarian relief.

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