Electromagnets

1. Electromagnets Lesson 6 How are electromagnets used?

2. What Is An Electromagnet? • A magnet that has coils of current-carrying wire around an iron core

3. Objective Students know the role of electromagnets in the construction of electric motors, electric generators, and simple devices, such as door bells and earphones

4. How are magnets used in our own backyard to produce electricity? Answer: at a wind farm! The wind spins turbines that use magnets and wires to produce electricity.

5. How do wind turbines make electricity? Why do you think that places like these are called “farms”? A wind turbine works the opposite of a fan. Instead of using electricity to make wind, like a fan, wind turbines use wind to make electricity. The wind turns the blades, which spin a shaft, which connects to a generator and makes electricity. Where in California would you expect to find places like this?

6. Name forms of energy? light electricity energy sound chemical energy thermal energy heat

7. Where does that word come from? Energy conversion- from the Latin word convertere which means “to turn”. Energy conversion means to turn one form of energy into another. Example- light or heat into electricity or sound. Kinetic- comes from the German worked kinein, which means “to move”. Kinetic energy is energy of motion.

8. Doorbells and Speakers A doorbell has an electromagnet with a freely moving rod. Pushing and releasing a button turns the current on and off. When the current is on, the rod moves into the coil. When the current is off, a spring pushes the rod out of the coil. A metal chime at each end of the rod makes the Ding! Dong! Speakers and earphones also have electromagnets. When you sing into a microphone, you send sound energy through the air. It then changes the sound energy into electrical energy that flows through wires as a current. The electrical energy is converted back into sound when it reaches the speaker.

9. Electric Motors An electric motor is a device that changes electrical energy into kinetic energy. Motors usually cause rotation, or a spinning motion. For a motor to keep turning, the current must keep changing direction. The coil becomes an electromagnet when it receives a current. The poles of the electromagnet are attracted to the opposite poles of the permanent magnet so the coils turns. As the direction of the current changes, the coil and permanent magnet keep attracting and repelling each other.

10. Generators A motor converts electrical energy into kinetic and other forms of energy. A generator is a machine that converts other forms of energy into electrical energy. Any kind of energy that can move a coil of wire inside a magnetic field can run a generator. In an emergency, people use a generator to provide electricity for the lights or a stove. Energy plants use huge generators that have electromagnets.

11. What does an electric motor do? A makes things stop running B changes kinetic energy to kinetic energy C changes electric energy to kinetic energy

12. What does a generator do? A It turns other forms of energy into electricity B It converts electrical energy into kinetic C It makes doorbells and speakers work

13. A student has a portable light that does not use a battery. She has to turn a handle very fast to make the light come on. What is inside the device? A a fuel B a motor C a generator D a wind turbine

14. Which of the following does not work by using an electromagnet? A blender B electric racing toy C compass D CD player

15. Can a speaker work without an electromagnet? Why or why not? A No, because the changing current in the electromagnet is what makes the speaker vibrate and produce sound waves. B Yes, the speaker can work without an electromagnet because the music makes the cone move

16. Let’s explore electromagnets and motors on hspscience… http://www.harcourtschool.com/menus/science/grade4_ca.html

17. The End