Question

Two lamps, one rated 100 W at 220 V and the other 200 W at 220V are connected
(i) in series and (ii) in parallel to electric main supply of 220V. Find the ratio of
heat produced in 2 sec in series to parallel​

Answer 1

Explanation:

Power, P=V2R

R1=50220×220=968Ω

R2=100220×220=484Ω

The equivalent resistance in the circuit,

Req=R1+R2

Req=968+484=1452Ω

The current flow in the circuit,

I=1452440=0.3030A

The voltage drop across bulb 1.

V1=iR1=0.3030×968=293.33V

The voltage drop across bulb 2.

V2=iR2=0.3030×484=146.65V

Bulb 1 will be fused because it can tolerate only 220 V but the voltage drop across it is 293.33V

The correct option is A.