A galvanometer with a resistance of 40.0 ω deflects full scale at a current of 2.0 ma. what resistance should be used with this galvanometer in order to construct a voltmeter that can read a maximum of 50 v?

The resistance needed to be added is R

The Current is 2 ma

The voltage reading is a maximum of 50 volts.

The ma meter has an internal resistance of 40 ohms.

Formula

E = I * R

Givens

E = 50

I = 2 ms

R = R + 40

Solution

E = I * R

I = 2 ma [ 1 amp / 1000 ma] = 0.002 amp

50 = 0.002 * (R + 40) Divide by 0.002

50/0.002 = R + 40

25000 = R + 40 Subtract 40 from both sides.

R = 25000 - 40

R = 24960 Answer