Question

An electric iron of resistance $20\Omega$ takes a current of $5A$. Calculate the heat developed in $30s$.

• A. $1.5\times {10}^{4}J$
• B. $2.8\times {10}^{4}J$
• C. $2.5\times {10}^{5}J$
• D. $2.5\times {10}^{4}J$

Answer 1

The correct option is A $1.5\times {10}^{4}J$

The amount of heat (H) produced is given by Joule's law of heating as, $H=Vlt$
Here, Current, $I=5A$
Time, $t=30s$
Voltage, $V=Current\times Resistance=5\times 20=100V$
$H=100\times 5\times 30=1.5\times {10}^{4}J$
Therefore, the amount of heat developed in the electric iron is $1.5\times {10}^{4}J$.