Question

A 40 W lamp requires 0.182 A current at 220 V while a 60 W lamp requires 0.272 A current at same volts.

If 40 W and 60 W lamps are connected in series with 220 V line, how many amperes of current will flow through

each lamp?​

Answer 1

Given info : A 40 W lamp requires 0.182 A current at 220 V while a 60 W lamp requires 0.272 A current at same volts. If 40 W and 60 W lamps are connected in series with 220 V.

To find : the current flowing through each lamp.

Solution : first find resistance of each lamp.

resistance of first lamp, R₁ = V²/P

= (220)²/40 = 1210 ohm

Resistance of 2nd lamp, R₂ = V²/P = (220)²/60 = 806.67 ohm

Now both lamps are joined in series combination, so equivalent resistance of lamps , Req = R₁ + R₂ = 1210 + 806.67 = 2016.67 ohm.

If appliances are joined in series, current passing through each appliance will be same.

Now current passing through each lamp, i = V/R = 220/2016.67 = 0.109 A

Therefore current will flow through each lamp is 0.109A