Question

Two tungsten bulbs of wattage 100 W and 60 W power work on 220 V potential difference. If they are connected in parallel, how much current will flow in the main conductor? (Ans : 0.72A). Solve the example

Answer 1

Potential remains same in the resistors when they are connected in the parallel. 
∴ Potential in both the bulbs will be same.  

Now, 
For First Tungsten Bulb, 
Power = 100 W.
Potential = 220 V.

∵ Power = Potential × Current. 
∴ Current = 100/220 
⇒ Current = 0.45 A.

For second Tungsten bulbs, 
Power = 60 W.
Potential = 220 V.

∴ Current = 60/220
   = 0.27 A.

Now, Total current flowing = Current in 1st bulb + Current in 2nd bulb.
     = 0.45 + 0.27
     =  0.72 A.


Hence, the total current flowing in the main conductor is 0.72 A.


Hope it helps.

Answer 2

Answer:

P1=100W

P2=60W

V=220V

I=?

P=VI

Explanation:

Total power=P1+P2

=100+60=160w

P=VI

I= P/V=160/220=8/11

I=0.72A

The current flowing in conductor=0.72A