A galvanometer having a resistance of 20 and 30 divisions on both sides has figure of merit 0.005 ampere/division. The resistance that should be connected in series such that it can be used as a voltmeter upto 15 volt, is :

a. |
80 |
b. |
120 |

c. |
125 |
d. |
100 |

A galvanometer having a resistance of 20 and 30 divisions on both sides has figure of merit 0.005 ampere/division. The resistance that should be connected in series such that it can be used as a voltmeter upto 15 volt, is :

a. |
80 |
b. |
120 |

c. |
125 |
d. |
100 |

1 Answer

127 votes

R_{g} = 200

N_{L} = N_{R }= N = 30

FOM = = 0.005 A/Div.

Current sentivity = CS = =

Ig_{max} = 0.005 × 30

= 15 × 10^{−2} = 0.15

15 = 0.15 [20 + R]

100 = 20 + R

R = 80

127 votes

127