Choose the letter of the correct answer. Write your answers on a separate sheet of paper.
a.
1. An electromagnet functions when
a you put a bulb into it
b. electricity flows through it
c. two objects rubbed together
d. you use a horseshoe magnet
2. Which of the following is TRUE about electromagnets?
A. They don't need a battery,
b. They are permanent magnets.
C. Increasing the number of coils makes the electromagnet stronger.
d. Increasing the number of battery makes the electromagnet weaker.
3. What is needed to make an electromagnet?
a nail, battery and a piece of wire
b. a bulb, battery and a piece of wire
c. a switch, plece of wire and a nail
d. a battery, switch and a piece of wire
4. How can you make an electromagnet stronger?
a. by using a bigger core
b. by adding switch into it
c. by increasing the length of the wire
d. Nothing can be done to increase the power of an electromagnet.
5. Which of the following electromagnets can attract the most number of thumbtacks?
a. one with 10 coils
b. one with 20 coils
c. one with 25 coils
d. one with 30 coils
6. What part of electromagnet receives electricity and acts as a magnet?
a. battery
C. switch
b. wire
d. core
7. Which from the following materials can be used as core in making an electromagnet?
a plastic ruler
C. Screw driver
b. plastic straw
d. wood stick
8. In which of the following materials can you make a stronger electromagnet?
a. one with 20 coils, 2 dry cells, wood as core
b. one with 20 coils, 1 dry cell, 1 big iron nail
c. one with 20 coils, 2 dry cells, plastic as core
d. one with 20 coils, 1 dry cell, 1 small iron nail
9. What will happen when electricity stops flowing through a coil of wire? A. The core will burn.
a. Nothing will happen to the core.
b. The core will stop attracting metal.
C. The core will continue attracting metal.
10. Which of the following materials uses an electromagnet?
a. ball and bat
c. fork and spoon
b. pen and paper
d. telephone and radio​​