Electromagnets — How They Work: Middle School Science Worksheet for 13-Year-Olds

Instructions

Read the explanation about how electromagnets work. Then, use what you've learned to complete all the activities that follow. You can check your answers using the answer key at the very end.

What is an Electromagnet?

An electromagnet is a special type of magnet that is created using electricity. Unlike the magnets on your refrigerator, which are always "on," an electromagnet can be turned on and off. This simple but powerful principle is behind many technologies we use every day, from scrapyard cranes to electric doorbells and computer hard drives.

So, how does it work? The magic happens when an electric current—the flow of tiny charged particles called electrons—moves through a wire. This moving current creates an invisible force field around the wire called a magnetic field. By itself, the magnetic field from a single straight wire is quite weak.

To make the magnetic field stronger, we can wrap the wire into a tight spiral, called a coil. Each loop of wire creates its own magnetic field, and when they are bundled together in a coil, their magnetic forces add up, creating a much stronger, more concentrated magnetic field.

To make it even more powerful, we can insert a piece of a specific type of metal, like iron, inside the coil. This metal piece is called the core. Iron is a "ferromagnetic" material, which means it can be easily magnetized. The magnetic field from the coil makes the iron core a strong magnet itself, and the core's magnetic field adds to the coil's field, creating a very powerful electromagnet. The best part? When you disconnect the battery and stop the electric current, the magnetic field disappears!

Activity 1: Label the Parts

Below is a description of a simple electromagnet. Identify the three main components labeled with numbers.

Description: A standard iron nail has a thin, insulated copper wire wrapped tightly around it many times. The two ends of this wire are connected to the positive (+) and negative (-) terminals of a battery, causing a current to flow.

1. The battery providing the power: ____________________
2. The iron nail inside the coil of wire: ____________________
3. The tightly wrapped wire: ____________________

Activity 2: Fill in the Blanks

Use the words in the word bank below to complete the sentences. Each word is used only once.

Word Bank:
stronger   |   core   |   current   |   off   |   magnetic field   |   coil

An electromagnet is a temporary magnet created when an electric ____________________ flows through a wire. Wrapping the wire into a ____________________ concentrates the invisible force called the ____________________. To make the electromagnet even ____________________, you can add an iron ____________________ inside the wire. Unlike a permanent magnet, an electromagnet can be turned ____________________ by cutting the power.

Activity 3: True or False?

Read each statement below. Circle T for True or F for False.

1. An electromagnet's magnetic field is permanent.     T / F
2. An electromagnet will work without a source of electricity.     T / F
3. Increasing the number of loops in the coil will make the electromagnet stronger.     T / F
4. The metal core of an electromagnet is usually made of a material like aluminum or plastic.     T / F
5. Electromagnets are useful because they can be switched on and off.     T / F

Activity 4: Think About It!

Answer the following questions in complete sentences.

1. You've built an electromagnet that can pick up 5 paper clips. Describe two different ways you could modify it to make it strong enough to pick up 15 paper clips.
   
   _________________________________________________________________________
   
   _________________________________________________________________________


2. What is the main advantage of an electromagnet compared to a regular, permanent magnet?
   
   _________________________________________________________________________
   
   _________________________________________________________________________

Answer Key

Activity 1: Label the Parts

1. Power Source (or Battery)
2. Core
3. Coil (or Conductor/Wire)

Activity 2: Fill in the Blanks

An electromagnet is a temporary magnet created when an electric current flows through a wire. Wrapping the wire into a coil concentrates the invisible force called the magnetic field. To make the electromagnet even stronger, you can add an iron core inside the wire. Unlike a permanent magnet, an electromagnet can be turned off by cutting the power.

Activity 3: True or False?

1. F
2. F
3. T
4. F (It is usually made of a ferromagnetic material like iron.)
5. T

Activity 4: Think About It!

(Note: Student answers should be similar to the examples below.)

1. To make the electromagnet stronger, you could:
   a) Increase the number of times the wire is wrapped around the core.
   b) Increase the electric current by using a more powerful battery (higher voltage).
2. The main advantage of an electromagnet is that its magnetism can be controlled. It can be turned on and off simply by starting or stopping the flow of electricity.