An ideal battery of 4 V and resistance R are connected in series in the primary circuit of a potentiometer of length 1 m and resistance 5 . The value of R, to give a potential difference of 5mV across 10 cm of potentiometer wire, is:

a. |
490 |
b. |
480 |

c. |
395 |
d. |
495 |

An ideal battery of 4 V and resistance R are connected in series in the primary circuit of a potentiometer of length 1 m and resistance 5 . The value of R, to give a potential difference of 5mV across 10 cm of potentiometer wire, is:

a. |
490 |
b. |
480 |

c. |
395 |
d. |
495 |

1 Answer

127 votes

Let current flowing in the wire is i.

i = A

If resistance of 10 m length of wire is x

then x = 0.5 = 5

V = P.d. on wire = i. x

5 10^{−3} = 0.5)

= 10^{−2} or R + 5 = 400

R = 395

127 votes

127