Question

A soldering iron draws an energy of $43200J$ in 4 min, when the current flowing through its element is $6A$, calculate the resistance of its heating element.

Answer 1

Hint:

$$\begin{gathered} W=I^{2}Rt \\ R=\frac{W}{I^{2}t} \end{gathered}$$

$R=$Resistance

$I=$Current

$t=$Time

Step 1:

Find the resistance of its heating element

Given data :

$w=43200J$

Current $=6A$

$t=$$4$ min

$W=I^{2}Rt$

$R=\frac{W}{I^{2}t}$

$$\begin{gathered} =\frac{43200J}{{\left(6A\right)}^2\left(4\times 60s\right)} \\ =\frac{43200J}{\left(6\times 6A^2\right)\left(4\times 60s\right)} \\ =\frac{43200}{\left(36\right)\left(240\right)} \\ =\frac{43200}{8640} \\ =5\Omega \end{gathered}$$

The resistance of its heating element is $5\Omega$.