Question

Which uses more energy, a $250\mathrm{W}$ TV set in $1\text{hr}$, or a $1200\mathrm{W}$ toaster in $10\text{minutes}$?

Answer 1

Step 1: Given data

Power of TV, $P_1=250\mathrm{W}$
Time of operation for TV set, $t_1=1\text{hr}$

Power of toaster, $P_2=1200\mathrm{W}$
Time of operation for toaster, $t_2=10\text{minutes}=\frac{1}{6}\text{hr}$

Step 2: Formulas used

We know that the power of electrical equipment is given as,
$P=\frac{E}{t}$
where $E$ is the energy consumed and $t$ is the time the electrical equipment is run for

Thus we have,
$E=Pt$

Step 3: Compare the energy consumed

Energy consumed by TV set is,
$\begin{array}{rcl}{E}_1& =& P_1{t}_1\\ & =& 250\times 1\\ \therefore E_1& =& 250\text{WH}\end{array}$

Therefore, energy consumed by TV set is $250\text{WH}$,

Energy consumed by toaster is,
$\begin{array}{rcl}{E}_2& =& P_2{t}_2\\ & =& 1200\times \frac{1}{6}\\ \therefore E_2& =& 200\text{WH}\end{array}$

Therefore, energy consumed by toaster is $200\text{WH}$,

Therefore, the energy consumed by $250\mathrm{W}$ TV set in $1\text{hr}$ is more than that by a toaster of $1200\mathrm{W}$ in $10\text{minutes}$.