Question

How many40 w 220v lamps can be safely connected to a 220v 5a line?

Answer 1

H=I²Rt (H proportional to R)

P=V²/R(P proportional to 1/R)
40=220×220/R
R=220×220/40
R=110×11

$\green{R=1210Ω}$

Max. no. of Resistance(n) to be connected
r=V/I
r=220/5

${\green{r=44}}$

Net Resistance
r=R/n
n=R/r
n=1210/44

${\green {n=27.5}}$

${\textbf{\blue{Hence we can connect 27 lamps safely}}}$

Hope it helps you :)

#$\red{Be Brainly}$