Question

A certain class of lamp takes 0.45A at 220V. How many such lamps can be run for an expenditure of power equal to 1 1/3 horsepower?

Answer 1

Power

P=IV

Now power

$P=0.45\times220=99W$

$P'=\frac{11}{3}$ Hp

$P'=\frac{11\times746}{3}=2735.33W$

Number of lamp=$\frac{P'}{P}$

$n=\frac{2735.33}{99}=27.62$

$n=27$ (Approximately)