Electricity Standard Grade

1. How much energy is transferred to a conductor connected to a 120V supply when a current of 4A flows for 3 minutes?

2. The heating element of an electric iron has a resistance of 24? and draws a current of 5A. How many joules of energy are transferred to the element while the iron is in use for 40 minutes?

3. An electric lamp uses energy at the rate of 60W when connected to a 12V supply.


a. the current in the lamp

b. the resistance of the lamp

4. A 12? resistor is connected to a 6V supply

a. What is the power dissipated in the resistor?

b. How long will it take for the resistor to gain 96J of internal energy

5. A resistor has a resistance of 24?. It is capable of dissipating energy at the rate of 6W.


a. the maximum current the resistor is able to carry

b. the maximum potential difference that should be applied across it

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