A 9.0-V battery costs $1.49 and will run a portable CD player for 6.0 hours before running down and needing to be replaced.If this battery supplies a current of 25 mA to the player,what is the cost of the energy provided by the battery in dollars per kWh?
A)$11/kWh
B)$110/kWh
C)$1100/kWh
D)$11,000/kWh

Question

Quizplus · Accepted Answer

First, we need to calculate the energy provided by the battery:
Energy = Power x Time
Power = Current x Voltage
Power = 0.025 A x 9 V = 0.225 W
Energy = 0.225 W x 6 hours = 1.35 Wh

To convert to kilowatt-hours, we divide by 1000:
1.35 Wh ÷ 1000 = 0.00135 kWh

Next, we need to calculate the cost of the energy provided:
Cost = Battery Cost ÷ Energy
Cost = $1.49 ÷ 0.00135 kWh = $1103.70/kWh

Rounding to the nearest cent, the answer is (C) $1100/kWh.

A 90-V Battery Costs $1