Question

A circuit has a line of 5A How many lamps of rating 40W and 220V can simultaneously glow on this line safely?​

Answer 1

Answer:

By using formula:

H=I(square)×R×T and

P=V(square)/R

Explanation:

h=40, I = 220v, R= ?

H=I(square)×R×T

40=220×220÷R

R=220×200÷40

R=1210 ohms

maximum number of resistance tube connected

r =V/I

r = 44 ohms

net resistance

r =R/n

n= 1210/44

n= 27.5

hence approximately we can connect 27 lamps safely