Assertion-Reason on Car Battery and Dry Cells – Rankers Physics

Combination of Batteries: Practice Problem & Solution

Assertion (A): A car battery is of \(12\text{ V}\). Eight dry cells of \(1.5\text{ V}\) connected in series can give \(12\text{ V}\). Still such cells are not used in starting a car. Reason (R): It is easier to start a car engine on a warm day than on a rainy day.  
Both (A) & (R) are true and the (R) is the correct explanation of the (A)
Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
(A) is true but (R) is false
Both (A) and (R) are false

Solution Explained:

To solve this problem, we apply the core principles of Combination of Batteries. Understanding the underlying formula is key to arriving at the correct answer below:

Assertion (A) is true: \(8 times 1.5\text{ V} = 12\text{ V}\). Dry cells have high internal resistance and cannot provide the high current needed to start a car. Reason (R) is also true, as engine oil is less viscous on a warm day. However, (R) does not explain (A).

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