n identical cells, each of emf `epsilon` and internal resistance r, are joined in series to form a closed circuit. One cell A is joined with reversed polarity. The potential difference across any one cell is

Options

A. zero
B. `epsilon`
C. `(epsilon)/(n)`
D. `(n -1)/(n)epsilon`

Answer

A

Explanation

Current in circuit, is `i8 = (n epsilon)/(nr) = (epsilon)/(r )`

The equivalent circuit of one cell is shown in fig.
The potential difference across the cell is `V_(A) - V_(B) =- epsilon +ir =`
`- epsilon +(epsilon)/(r )r= 0`