Question

Two electric lamps of each 40 watt are connected in series. The power consumed by the combination will be

Options

• 20 Watt

• 60 Watt

• 80 Watt

• 100 Watt

Answer 1

20 Watt

Explanation:

Each bulb's resistance = V²/40 ohm.

Total resistance of two bulbs connected in series

R = `V^2/40 + V^2/40 = V^2/20`

As a result, the effective power of two bulbs is

R = `V^2/R = V^2/(V^2/20)` = 20 watt