Current, potential difference and resistanceEdexcel International A Level Physics: Mind map

Exam questions on Current, potential difference and resistance

1. A student connects a small electric motor to a 6.0 V battery of negligible internal resistance. The motor draws a steady current of 0.50 A for 3.0 minutes, and the whole 6.0 V is across the motor.
   Calculate the number of electrons that pass through the motor in this time. (Elementary charge e = 1.60 × 10⁻¹⁹ C.)2 marks
2. A student investigates a length of nichrome wire kept at a constant temperature in a water bath. She measures the current for different potential differences across the wire and records: 0.10 A at 0.50 V, 0.20 A at 1.00 V, 0.30 A at 1.50 V and 0.40 A at 2.00 V.
   Use the student's data to decide whether the wire obeys Ohm's law. Justify your answer.2 marks
3. During a thunderstorm a lightning flash lasts 2.0 ms. A total charge of 24 C is transferred between the cloud and the ground through a potential difference of 1.5 × 10⁸ V. A metal lightning conductor on a nearby building carries the discharge and has a resistance of 0.015 Ω.
   Calculate the mean current during the flash and the energy transferred.3 marks