A Level Physics Practice Exam

What happens when the internal resistance of a car battery is too high?

1. It increases efficiency of the battery

2. It decreases the energy loss

3. It makes it harder to start the car

4. It improves battery performance

The correct answer is: It makes it harder to start the car

When the internal resistance of a car battery is too high, it leads to several issues related to the battery's ability to supply energy effectively. A key consequence of high internal resistance is that it impedes the flow of current from the battery. In a car, a significant amount of current is required to start the engine, typically measured in hundreds of amps. When the internal resistance increases, it generates more heat and causes a voltage drop across the battery terminals when the current is drawn. As a result, the voltage available to the starter motor becomes insufficient for starting the engine. This means that even if the battery has sufficient charge, the effective voltage reaching the motor may not be enough to initiate the starting process. Therefore, a car with a battery that has high internal resistance will experience difficulty in starting, as it cannot provide the necessary current effectively. This is particularly problematic in cold weather or when the car has not been used for a while, as these conditions can further compound starting issues. In summary, high internal resistance in a car battery restricts current flow, causing difficulties in starting the vehicle, which aligns with the situation described in the correct answer.