Question

Question 4.27: A galvanometer coil has a resistance of 12 Ω and the metre shows full scale deflection for a current of 3 mA. How will you convert the metre into a voltmeter of range 0 to 18 V?

Class 12 - Physics - Moving Charges And Magnetism Moving Charges And Magnetism Page-172

Answer 1

$\text{by putting formula}\\\\\bf{R_V=\frac{V}{I_g}-G}\\\\\text{we can calculate required resistance to be connected in series}\\\\\bf{R_v=\frac{18}{3\times10^{-3}}-12=5988\Omega}$

[here V is maximum potential range of voltmeter,
Ig is the current passing through galvanometer,
G is the resistance of galvanometer.]

Answer 2

Answer:

Converting galvanometer into voltmeter is done by adding resistance in series.

The resistance is given by R=IgV−G; G is resiatance of galvanometer.

⇒R=5988Ω