Physics

Problem

An electric heater is operated at a constant potential difference

V

across a fixed resistance

R

for a time interval

t

. (a) Using dimensional arguments, show that the expression

\dfrac{V^{2}}{R}\,t

has the dimensions of energy. (b) The heater is rated

230\,\text{V}

and

2.0\,\text{kW}

. Calculate the electrical energy supplied to it in

30\,\text{min}

and express your answer in both joule and kilowatt-hour.