Question

A domestic lighting circuit has a fuse of $5\text{A}$. If the main supply is at $230\text{V}$. Calculate the maximum number of $36\text{W}$ tube-lights that can be safely used in this circuit.

• A. $22$
• B. $31$
• C. $47$
• D. $12$

Answer 1

The correct option is B $31$

Let the maximum number of tube - lights that can be used safely is $N$.

Power consumed by $N$ tube lights is,

$P=36N$

The maximum power that can be drawn is,

$P_{max}=230\times 5=1150$

So,

$36N=1150$

$\Rightarrow N=\frac{1150}{36}=31.94$

Therefore, the maximum number of tube lights that can be used are $31$.

Hence, option $\left(B\right)$ is the correct answer.