Two moving coil meters `M_1 " and " M_2` have the following particulars
`R_1 = 10 omega, N_1 = 30 , " "A_1 = 3.6 xx 10^(-3) m^2, B_1 = 0.25 T`
`R_(2) =14 omega , N_2 = 42 A_(2) = 1.8 xx 10^(-3) m^2, B_(2) = 0.50 T`
(The spering constants are identical for the two meters )
Determine the ratio of (a) current sensitivity and (b) voltage sensitivity of `M_2 "and "M_1`

Explanation

Current sensitivity , `(theta )/(I) = (BAN)/(C)`
Ratio of second to first is `((B_2A_2N_2)/(C_2))/((B_1A_1N_1)/(C_1))= (0.5 xx 1.8 xx 10^(-3) xx 42)/(0.25 xx 3.6 xx 10^3)=7/5 =1.4`
b. Voltage sensitivity `(theta)/(V) = (BAN)/(C) xx 1/R`
`1.4 xx (R_1)/(R_2) = 1.4 xx (10)/(14) =1`