Question

Consider an electric motor having resistance of 10 Ω, 20 Ω and 30 Ω respectively. The percentage of energy dissipated by 10 Ω earthing plate is ____________

(a) More than 50% of total energy

(b) Less than 50% of total energy

(c) Depends on the materials of the three plates

(d) May be more or less than 50% of total energy

I had been asked this question in semester exam.

This intriguing question originated from Advanced Problems on Network Theorems in division Useful Theorems in Circuit Analysis of Network Theory

Answer 1

Right answer is (a) More than 50% of total energy

The explanation: The parallel combination of 30 Ω and 20 Ω is 12 Ω. Since 12 Ω and 10 Ω are in parallel, the 10 ohm plate draws more than 50% current and dissipates more than 50% energy.