Question

A teacher asked a student to connect N cells each of emf e in series to get a total emf of Ne. While connecting, the student, by mistake, reversed by polarity of n cells. The total emf of the resulting series combination is:

• A. $e\left( N-\frac{n}{2} \right)$
• B. $e\left( N-n \right)$
• C. $e\left( N-2n \right)$
• D. $eN$

Answer 1

Answer: (C)

$e\left( N-2n \right)$

Answer 2

If polarity of n cells out of N cells is reversed, then equivalent emf $=(N-2n)e$