Energy equivalence — verify the statement: consuming 4 kWh of electrical energy is equivalent to drawing 2000 W of power for 2 hours (energy = power * time).

Introduction / Context:Utility bills quote energy in kilowatt-hours (kWh). Converting between energy and power-time products is essential both for household consumption and engineering estimates. The statement equates 4 kWh with 2000 W sustained for 2 hours; this is a straightforward application of E = P * t.

Given Data / Assumptions:

• Energy E = 4 kWh.
• Proposed power-time pair: P = 2000 W, t = 2 h.
• We consider real power; reactive aspects average to zero for energy billing.

Concept / Approach:Convert units carefully: 1 kW = 1000 W. Energy in kWh is the time integral of kilowatts. If power is constant, E = P * t. Therefore, 2000 W * 2 h = (2 kW) * 2 h = 4 kWh. The equality holds irrespective of DC or AC, provided P denotes real power over the interval.

Step-by-Step Solution:

Verification / Alternative check:Another equivalent: 1000 W for 4 h or 4000 W for 1 h also yield 4 kWh. Any P, t pair with P(kW) * t(h) = 4 satisfies the same energy.

Why Other Options Are Wrong:

• Incorrect: contradicts the direct unit calculation.
• “Only DC” or “only at unity PF”: Energy calculation E = ∫ P_real dt remains valid in AC; utility meters measure real energy.
• “Need voltage”: Voltage is unnecessary if power is already given.

Common Pitfalls:Mixing up kWh (energy) and kW (power); forgetting to convert W to kW before multiplying by hours.

Final Answer:Correct — 2000 W for 2 h equals 4 kWh of energy.