Question

An electric toaster of resistance $80\Omega$ takes a current of $10A$. Calculate the heat developed in $2minutes$.

Answer 1

Step 1: Given data and formula used

Given data:

1. Resistance of the electric toaster is $R=80\Omega$
2. Current flowing through the toaster is $I=10A$
3. Time for which current flows is $t=2minutes=2\times 60s=120s$

Formula:

According to Joule's law of heating, the amount of heat developed $\left(H\right)$ in a conductor is

$H=I^{2}Rt$

Step 2: Finding the value of heat developed

Substituting the values of current, resistance, and time into the equation to calculate heat developed.

$$\begin{gathered} H={\left(10A\right)}^2\left(80\Omega \right)\left(120s\right) \\ H=100\times 80\times 120 \\ H=960000J\left(1kJ=1000J\right) \\ H=960kJ \end{gathered}$$

Thus, the heat developed in $2minutes$ is $960kJ$.