If the charge of electricity is K wh is N4, what is the cost of operating an electrical appliance rated 250 v,2 A for six hours?

Analyze the question: The question is garbled. "K wh" should be "kWh" (kilowatt-hour), so the charge is N4 per kWh. We need the cost of running a 250 V, 2 A appliance for 6 hours.

Concept: Electrical energy used is

Energy (kWh) = Power (kW) × Time (hours), where Power = V × I

Solution:

1. Power = V × I = 250 × 2 = 500 W = 0.5 kW
2. Energy = 0.5 kW × 6 h = 3 kWh
3. Cost = 3 × N4 = N12

Tip: In "cost of electricity" questions, always do these steps in order:

1. P = VI (convert to kW by dividing by 1000)
2. Energy = P × t (in hours)
3. Cost = Energy × rate

Many students lose marks by forgetting to convert watts to kilowatts. Check that your units are kWh before multiplying by the rate.