A battery charger is connected to a dead battery and delivers a current of 4.5 A for 6.0 hours, keeping the voltage across the battery terminals at 12 V in the process. How much energy is delivered to the battery?
Power(W) x Time (s) = Energy (Joules)
The power in watts is (Volts)x(Amperes)
Now do the numbers.
If these equations are not familiar to you by now, you are not learning much physics.
To calculate the amount of energy delivered to the battery, we can use the formula:
Energy = Power x Time
First, let's calculate the power using the formula:
Power = Voltage x Current
In this case, the voltage is 12 V and the current is 4.5 A. So,
Power = 12 V x 4.5 A = 54 W
Now we have the power (54 W) and the time (6.0 hours), so we can calculate the energy:
Energy = 54 W x 6.0 hours
To multiply the power (54 W) by the time (6.0 hours), we multiply the numerical values together and the unit (hours) cancels out, leaving us with the unit of energy, which is joules (J).
Energy = 54 W x 6.0 hours = 324 J
Therefore, the battery charger delivers 324 joules of energy to the battery.
To calculate the energy delivered to the battery, we can use the formula:
Energy = Current × Voltage × Time
Given that the current is 4.5 A, the voltage is 12 V, and the time is 6.0 hours, we can substitute these values into the formula:
Energy = 4.5 A × 12 V × 6.0 hours
Calculating this expression:
Energy = 324 watt-hours (or 324 Wh)