question_answer

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

Answer:

Given, \[I=5A,\]

No. of lamps = n, and

Power,    P = 40 W

Power of 1 bulb = 40 W

Power of n bulbs = 40n watt

We know,

\[P=V\times I\]

\[40n=220\times 5\]

\[\Rightarrow \]   \[n=\frac{220\times 5}{40}=\frac{55}{2}=27.5\]

\[\therefore \]      No. of lamps = 27