|TAP 108- 2: Introductory questions on resistance
1. Convert the following:
(a) 12 500 Ω to kΩ
(b) 0.025 kΩ to Ω
2. A 240 V lamp draws a current of 0.50 A from the mains supply. What is the resistance of the lamp?
3. What current flows through a 12 V lamp when its filament has a resistance of 100 ? Give your answer in amps and milliamps.
4. A current of 4.0 mA flows through a fine piece of resistance wire when the potential difference across it is 8.0 V. What is the resistance of the wire?
5. A 5000 V EHT supply is protected by a 5 mega-ohm (5 M) resistor in series with its positive terminal. What is the maximum current that can be drawn from this supply if its terminals are shorted? (Ignore its internal resistance)
1 (a) 12.5 Ωk (b) 25 Ω
2. 480 Ω
3. 0.12 A or 120 mA
4. 2000 or 2.0 k
5. 0.001 A or 1.0 mA