Question

A circuit has a line of 5 A. How many lamps of rating 40 W; 220 V can simultaneously run on this line safely?

• A. $44$
• B. $8$
• C. $27$
• D. $20$

Answer 1

The correct option is C $27$

Given : $P=40$ W $V=220$ volts

Safe current through each lamp $i=\frac{P}{V}=\frac{40}{220}=0.18$ A

$\therefore$ Number of lamps can be safely used $n=\frac{I}{i}=\frac{5}{0.18}=27$ lamps