# Class 12 Physics Moving Charges and Magnetism: NCERT Solutions for Question 10

This page focuses on the detailed Moving Charges and Magnetism question answers for Class 12 Physics Moving Charges and Magnetism, addressing the question: 'Two moving coil meters, M1 and M2 have the following particulars: R1 = 10 Ω, N1 = 30, A1 = 3.6 x 10-3 m2, B1 = 0.25 T R2 = 14 Ω, N2 = 42, A2 = 1.8 x 10-3 m2, B2 = 0.50 T (The spring constants are identical for the two meters). Determine the ratio of (a) current sensitivity and (b) voltage sensitivity of M2 and M1.'. The solution provides a thorough breakdown of the question, highlighting key concepts and approaches to arrive at the correct answer. This easy-to-understand explanation will help students develop better problem-solving skills, reinforcing their understanding of the chapter and aiding in exam preparation.
Question 10

## Two moving coil meters, M1 and M2 have the following particulars:R1 = 10 Ω, N1 = 30,A1 = 3.6 x 10-3 m2, B1 = 0.25 TR2 = 14 Ω, N2 = 42,A2 = 1.8 x 10-3 m2, B2 = 0.50 T(The spring constants are identical for the two meters).Determine the ratio of (a) current sensitivity and (b) voltage sensitivity of M2 and M1.

For moving coil meter M1:

Resistance, R1 = 10 Ω

Number of turns, N1 = 30

Area of cross-section, A1 = 3.6 × 10-3 m2

Magnetic field strength, B1 = 0.25 T

Spring constant K1 = K

For moving coil meter M2:

Resistance, R2 = 14 Ω

Number of turns, N2 = 42

Area of cross-section, A2 = 1.8 × 10-3 m2

Magnetic field strength, B2 = 0.50 T

Spring constant, K2 = K

(a) Current sensitivity of M1 is given as:

And, current sensitivity of M2 is given as:

so,  Ratio

Hence, the ratio of current sensitivity of M2 to M1 is 1.4.

(b) Voltage sensitivity for M2 is given as:

And, voltage sensitivity for M1 is given as: