An incandescent electric bulb converts 20% of its power consumption into light, and the remaining power is dissipated as heat. The bulb's filament has a resistance of 200 22 and 2 A current flows through it. If the bulb remains ON for 10 h and the rate of electricity charge is ₹5/unit, then which among the following is the correct amount for the money spent on producing light ?

To determine the money spent on producing light, we first calculate the total power consumption and the resulting electricity bill.

• Power (P): Using the formula P = I²R, where I = 2 A and R = 200 Ω, Power = 2² × 200 = 4 × 200 = 800 Watts (0.8 kW).
• Energy Consumed: Energy = Power × Time. For 10 hours, Energy = 0.8 kW × 10 h = 8 kWh. In electrical terms, 1 kWh equals 1 unit.
• Total Cost: At a rate of ₹5 per unit, the total cost for 8 units is 8 × ₹5 = ₹40.

The problem states that the bulb converts 20% of its power consumption into light. Therefore, the portion of the total cost spent specifically on producing light is:

• Cost for Light: 20% of ₹40 = 0.20 × 40 = ₹8.

Hence, Option D is the correct answer.