Chapter 22, Problem 78A

To determine

Thermal energy output.

Answer to Problem 78A

  $E=1.189\times {10}^6\text{J}$

Explanation of Solution

Given:

Voltage rating of iron, $V=110\text{V}$

Current drawn, $I=3\text{A}$

Time, $t=1\text{h}=3600\text{s}$

Formula Used:

The energy power relation is,

  $E=Pt$

Where, $E$ is energy, $P$ is electric power and $t$ is time

The electrical power is given as,

  $P=VI$

Where, P is electrical power, $V$ is applied voltage and I is current produced.

Calculation:

From the above relations, the thermal energy

  $Q=E=Pt=VIt$

So, on substituting the values

  $\begin{array}{c}E=110\times 3\times 60\\ =1.189\times {10}^6\text{J}\end{array}$

Conclusion:

Therefore, the thermal energy output of iron is $E=1.189\times {10}^6\text{J}$