Electricity and Circuits — Answer Key
Part A: Fill in the Blank
Write the missing word or number on each line.
1. A circuit breaker automatically shuts off electricity when a circuit overloads.
A circuit breaker is a reusable safety switch that trips (opens) automatically when too much current flows.
2. Static electricity builds up when objects gain or lose electrons.
Static electricity is a charge imbalance caused by friction transferring electrons between objects.
3. Lightning is a natural form of electrical discharge.
Lightning is a massive electrical discharge caused by charge buildup in storm clouds.
4. The positive and negative ends of a battery are called terminals.
A battery has a positive terminal (+) and negative terminal (−). Current flows from negative to positive through the circuit.
5. Volts measure the amount of electrical energy a battery provides.
Voltage (measured in volts) represents the electrical potential energy per unit charge that drives current.
6. A complete circuit must include a source of energy, a load, and connecting wires.
A 'load' is any device (bulb, motor, etc.) that uses the electrical energy. Without a load, you have a short circuit.
7. Thick wires carry more current than thin wires.
Thicker wires have lower resistance, allowing more current to flow safely.
8. Rubbing a balloon on your hair creates static electricity.
Friction transfers electrons from hair to balloon, creating static charge that can attract small objects.
9. Never fly a kite near power lines because electricity can travel through the string.
Power lines carry high-voltage electricity. A damp kite string could conduct electricity from the line to the person holding it.
Part B: Matching
Match each item on the left to the correct answer on the right.
1. Match each item to its correct answer.
series circuit
→ one path for electricity to flow
reusable switch that stops excess current
parallel circuit
→ multiple paths for electricity to flow
one path for electricity to flow
fuse
→ thin wire that melts to break a circuit
multiple paths for electricity to flow
circuit breaker
→ reusable switch that stops excess current
thin wire that melts to break a circuit
Series circuit → one path; parallel circuit → multiple paths; fuse → thin wire that melts; circuit breaker → reusable switch.