The values of potential difference V applied across a resistor and the corresponding values of current I flowing in the resistor are given below :
Potential difference, V (in volts): | 2.5 | 5.0 | 10.0 | 15.0 | 20.0 | 25.0 |
Current, I (in amperes) | 0.1 | 0.2 | 0.4 | 0.6 | 0.8 | 1.0 |
Plot a graph between V and I, and calculate the resistance of the resistor.
The table below shows the current in three different electrical appliances when connected to the 240 V mains supply:
Appliance | Current |
Kettle | 8.5 A |
Lamp | 0.4 A |
Toaster | 4.8 A |
(a) Which appliance has the greatest electrical resistance? How does the data show this?
(b) The lamp is connected to the mains supply by using a thin, twin-cored cable consisting of live and neutral wires. State two reasons why this cable should not be used for connecting the kettle to the mains supply.
(c) Calculate the power rating of the kettle when it is operated from the 240 V mains supply.
(d) A man takes the kettle abroad where the mains supply is 120 V. What is the current in the kettle when it is operated from the 120 V supply?