Question

You have two electric lamps. The printed specifications on them are 40W,
220V and 100W, 220 V. Calculate the current and resistance of each lamp
when put in a circuit of 220 V supply line.

Answer 1

Explanation ⇒ For Bubl 1,

P = 40 W, V = 220 V.

Using the formula,

Current = Power/Voltage.

∴ Current = 40/220

∴ Current = 0.18 A.

Resistance = (V)²/P

∴ R = 220 × 220/40

R = 1210 Ω

Now,

For Bulb 2,

P = 100 W

V = 220 V.

Thus, Current = P/V

∴ i = 100/220

∴ i = 0.45 A.

Also, Resistance = (V)²/P

Resistance = (220)²/100

∴ R = 484 Ω

Hope it helps.

Answer 2

Answer:

For Bubl 1,

P = 40 W, V = 220 V.

Using the formula,

Current = Power/Voltage.

∴ Current = 40/220

∴ Current = 0.18 A.

Resistance = (V)²/P

∴ R = 220 × 220/40

R = 1210 Ω

Now,

For Bulb 2,

P = 100 W

V = 220 V.

Thus, Current = P/V

∴ i = 100/220

∴ i = 0.45 A.

Also, Resistance = (V)²/P

Resistance = (220)²/100

∴ R = 484 Ω