A device for heating a cup of water in a car connects to the car\'s battery, whi

Question

A device for heating a cup of water in a car connects to the car's battery, which has an emf = 10.0 and an internal resistance = 0.05 . The heating element that is immersed in the cup of water is a resistive coil with resistance .
David wants to experiment with the device, so he connects an ammeter into the circuit and measures 12.0 when the device is connected to the car's battery. From this, he calculates the time to boil a cup of water using the device. If the energy required is 100 , how long does it take to boil a cup of wa
Part D
The energy delivered to the resistive coil is dissipated as heat at a rate equal to the power input of the circuit. However, not all of the energy in the circuit is dissipated by the coil. Because the emf source has internal resistance, energy is also dissipated by the battery as heat. Calculate the rate of dissipation of energy in the battery.
Express your answer in watts using three significant figures.

Explanation / Answer

Energy gets converted to heat at a rate of (I^2)*r where r is the internal resistance of the battery in this case. Therefore, P_bat = 12^2 * .04 ohms, so P_bat = 5.76W

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