Physics

Problem

A copper-wire heating element of resistance

30\,\Omega

is immersed in

0.50\,\text{kg}

of water initially at

20^{\circ}\text{C}

. The element is connected to a

230\,\text{V}

mains supply. Neglect heat losses to the surroundings and take the specific heat capacity of water as

4.2 \times 10^{3}\,\text{J}\,\text{kg}^{-1}\,^{\circ}\text{C}^{-1}

. a. (i) Calculate the energy required to raise the temperature of the water to its boiling point at

100^{\circ}\text{C}

. b. (ii) Determine the time needed for the heater to supply this energy.