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The battery of an electric car consists of 30 cells, connected in series, to supply current to the

motor.

(a) Assume that the internal resistance of each cell is negligible and that the pd across each

cell is 6.0V.

(i) State the pd across the motor.

(ii) The battery provides 7.2kW to the motor when the car is running. Calculate the

current in the circuit.

(iii) The battery can deliver this current for two hours. Calculate how much charge

the battery delivers in this time

(iv) Calculate the energy delivered to the motor in the two hour period.

b)In practice, each cell has a small but finite internal resistance. Explain, without

calculation, the effect of this resistance on

- the current in the circuit, and

- the time for which the battery can deliver the current in part (a)(ii).

You may assume that the motor behaves as a constant resistance.

I can do part (a) with ease, and the first part of b also. However, I am unable to do the part of b which asks for the effect of internal resistance on the time for which the battery can deliver the current in part (a)(ii).

Please can someone help me with this.

Thanks

motor.

(a) Assume that the internal resistance of each cell is negligible and that the pd across each

cell is 6.0V.

(i) State the pd across the motor.

(ii) The battery provides 7.2kW to the motor when the car is running. Calculate the

current in the circuit.

(iii) The battery can deliver this current for two hours. Calculate how much charge

the battery delivers in this time

(iv) Calculate the energy delivered to the motor in the two hour period.

b)In practice, each cell has a small but finite internal resistance. Explain, without

calculation, the effect of this resistance on

- the current in the circuit, and

- the time for which the battery can deliver the current in part (a)(ii).

You may assume that the motor behaves as a constant resistance.

I can do part (a) with ease, and the first part of b also. However, I am unable to do the part of b which asks for the effect of internal resistance on the time for which the battery can deliver the current in part (a)(ii).

Please can someone help me with this.

Thanks

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