Question

Two lamps one rated 100 watt at 220 volt and the other 200 watt at 220 volt are connected in series and parallel electric main supply of 220 volt .Find the current draw in each case?

Answer 1

P=VI;---------------------------------------------------------------POWER RATING

100=I*220;

I=0.45 A;

therefore, resistance=V/I;----------------------------------OHM'S LAW

R=220/0.45;

R=488.89;

I round the value and take it as 489 ohms;

the same process is done for the other bulb and the resistance for it is 241.76 ohms;

so if the resistors are connected in series the sum is the equivalent resistance;

R1+R2=488.89+241.76=730.65 ohms;

so the current=220/730.65;

I=0.3;

therefore current in case of series connection is equal to 0.3 amperes;

so if the resistors are connected in parallel the product divided by the sum is the equivalent resistance;

R1+R2=488.89+241.76=730.65 ohms;

R1*R2=488.89*241.76=1,18,194.05

so the current=1,18,194.05/730.65;

I=161.77;

therefore current in case of parallel connection is equal to 161.77 amperes;