WAEC - Physics (2005 - No. 37)
An electric lamp is rated 240V, 40W. What is the cost of running the lamp for 72 hours if the electricity authority charges N2.50 per kWh?
N7.20
N18.00
180.00
N720.00
คำอธิบาย
Cost = \(\frac{Pt}{1000}\) x cost per kWh
= \(\frac{40 \times 72}{1000} \times 2.50 = N7.20\)
= \(\frac{40 \times 72}{1000} \times 2.50 = N7.20\)