Question

A 20uf capacitor is charged by a 30v dc supply and then connected across an uncharged 50uf capacitor. Calculate the final potential difference across the combination

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.