Electricity and Circuits — Answer Key
Part A: Fill in the Blank
Write the missing word or number on each line.
1. Rubbing two objects together can transfer electrons from one object to the other.
Friction from rubbing knocks loose electrons off one surface and deposits them on the other, which is why one object gains a negative charge and the other loses it.
2. A television converts electrical energy into light and sound energy.
A television screen produces light so you can see the picture, and its speakers produce sound so you can hear the audio -- both powered by electrical energy.
3. A material that slows or stops the flow of electricity is called an insulator.
Insulators like rubber and plastic hold their electrons tightly, which prevents electric current from passing through and keeps people safe from shocks.
4. When a negatively charged balloon is brought near small pieces of paper, the paper is attracted to the balloon.
The balloon's negative charge pulls the positive charges in the paper toward it. Since the paper is light enough, this pulling force lifts the pieces right up to the balloon.
5. A motor converts electrical energy into mechanical energy to make things spin.
A motor uses magnets and coils of wire to turn electrical energy into mechanical energy -- the spinning motion that powers fans, toys, and many machines.
6. The rapid movement of electrons through a conductor is called electric current.
Electric current is the steady flow of electrons moving through a conductor like copper wire, similar to how water current is water flowing through a pipe.
7. Two balloons that are both negatively charged will repel each other when brought close together.
Both balloons carry the same negative charge, and like charges always push away from each other, so the balloons move apart when brought close together.
8. An electric lightning is a sudden discharge of static electricity between a cloud and the ground.
Lightning is a giant spark of static electricity. Charges build up in storm clouds until the difference is so large that electrons jump all the way to the ground in a powerful discharge.
9. The part of a circuit that uses electricity to do work is called the load.
The load is any device in the circuit that converts electrical energy into another form of energy, such as a bulb (light), a buzzer (sound), or a heater (heat).
Part B: Matching
Match each item on the left to the correct answer on the right.
1. Match each item to its correct answer.
copper wire
→ carries electricity through a circuit
sudden discharge of built-up charge
rubber gloves
→ protects hands from electric current
converts electrical energy to light
light bulb
→ converts electrical energy to light
carries electricity through a circuit
static shock
→ sudden discharge of built-up charge
protects hands from electric current
Correct matches: copper wire → carries electricity through a circuit; rubber gloves → protects hands from electric current; light bulb → converts electrical energy to light; static shock → sudden discharge of built-up charge.