A resistance R is connected across the terminal of an electric cell of internal resistance…

A resistance R is connected across the terminal of an electric cell of internal resistance 2Ω and the voltage was reduced to 3/5 of its nominal value.
The value of R is
  • A.
    3 Ω
  • B.
    2 Ω
  • C.
    1 Ω
  • D.
    6 Ω
Correct Answer: Option A
Explanation

1 = V/R = E/R+r , if r = 2Ω
V = 3/5 E
=> 3E/5R = E/R+2
i.e 3E(R+2) = 5RE
3RE + 6E = 5RE
i.e 3R + 6 = 5R
6 = 5R – 3R
=> 2r = 6 i.e R = 6/2 = 3Ω

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