Energy Transfers in Circuits Quiz
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5 questions, one answer each
Each answer is checked as you go, with why.
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1. Why does a wire heat up when carrying a current?
- A. Electrons collide with ions in the lattice, transferring energy to them
- B. The wire absorbs light from the surroundings
- C. Current flows faster than usual through resistive wires
- D. Magnetic fields around the wire cause heating
2. Which equation correctly gives electrical power?
- A. P = I ÷ V
- B. P = I × V
- C. P = V ÷ I
- D. P = I − V
3. A heater has a current of 5 A and a resistance of 10 Ω. What is the power dissipated?
- A. 2 W
- B. 15 W
- C. 50 W
- D. 250 W
4. Why are low-resistance wires used for connecting cables in circuits?
- A. To increase the heating effect for warmth
- B. To reduce unwanted energy transfer (heating) in the wires
- C. To make the wires more magnetic
- D. To increase the current-carrying capacity indefinitely
5. Two lamps, A (60 W) and B (100 W), are switched on for the same length of time. Which statement is correct?
- A. Lamp A transfers more energy than lamp B
- B. Lamp B transfers more energy than lamp A
- C. Both lamps transfer exactly the same energy
- D. Power rating has no effect on energy transferred