Question

A kettle is rated at 1 kW, 220 V. Calculate the working resistance of the kettle.

Resistance = ...........
When connected to a 220 V supply, it takes 3 minutes for the water in the kettle to reach boiling point. Calculate how much energy has been supplied?

Answer 1

Step-by-step explanation:

Power of electric kettle, P = 1 kW

Voltage, V = 220 V

(a) Electric power is given by the formula as follows :

`P=(V^2)/(R)`

R is resistance

`R=(V^2)/(P)\\\\R=((220)^2)/(10^3)\\\\R=48.4\ \Omega`

(b) When connected to a 220 V supply, it takes 3 minutes for the water in the kettle to reach boiling point.

Energy supplied is given by :

`E=P* t`

P is power,
`P=(V^2)/(R)`

`E=(V^2)/(R)t\\\\E=((220)^2)/(48.4)* 180\\\\E=180000\ J\\\\E=180\ kJ`