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Question
Two non-ideal batteries are connected in series. Consider the following statements:-
(A) The equivalent emf is larger than either of the two emfs.
(B) The equivalent internal resistance is smaller than either of the two internal resistances.
Options
A and B are correct
A is correct but B is wrong
B is correct but A is wrong
A and B are wrong
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Solution
A is correct but B is wrong
Let the emfs of the batteries be e1 and e2, and their respective resistances be r1 and r2.
Since the batteries are connected in series, the equivalent emf will be the sum of the emf of the two batteries ( e = e1 + e2) .
Thus, e > e1 and e > e2
Thus, the equivalent emf is larger than either of the two emfs. Hence, statement A is correct.
Since the batteries are connected in series, the equivalent internal resistance (r) of the combination will be the sum of the internal resistance of the two batteries ( r = r1 + r2).
r > r1 and r > r2
Thus, the equivalent internal resistance is greater that either of the two resistances. Hence, statement B is wrong.
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