Question

'n' number of identical cells in series
grouping all in same order. Have a
total emf of 15V. When any one cell is
reversed the emf becomes 12V. The
number 'n' will be​

Answer 1

Answer:

10

Explanation:

Emf reduced = 15V-12V=3V

If one cell is reversed, effect of two cells are cancelled.

Accorsing to qsn, one cell is reversed .

So for cancellation of 3V cell must be 2.

    for cancellation of 1V cell must be 2÷3.

Hence, no of cell= (2÷3)*15 = 10

Answer 2

The number 'n' will be 54.

The number 'n' will be 54.To find:

The change in number of identical cells 'n'

Solution:

Let us take emf as E.

• E = Voltage × no of cells / 4
• E = V × n / 4

The change in emf is

• 15V - 12V = 3V

Given, one cell is reversed,

Hence, the voltage will be constant.

• 15V = n/4
• 60V = n
• 12V = (n-1)/4
• 48V = n-1
• 108V = 2n -1
• n = 54

Hence, the number 'n' will be 54.

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