Mathematics

Problem

An immersion heater of resistance

20\,\Omega

is used to raise the temperature of

0.5\,\text{kg}

of water from

25^{\circ}\text{C}

45^{\circ}\text{C}

5\,\text{min}

. Assuming no heat is lost to the surroundings and taking the specific heat capacity of water as

4200\,\text{J\,kg}^{-1}\,^{\circ}\text{C}^{-1}

, determine the current drawn by the heater. a)

4.0\,\text{A}

2.65\,\text{A}

7.0\,\text{A}

1.9\,\text{A}