In a moving coil galvanometer, two moving coils M_1 and M_2 have the following particulars: R_1=5 Ω, N_1=15, A_1=3.6 × 10^-3 m^2, B_1=0.25 T; R_2=7…

In a moving coil galvanometer, two moving coils $\displaystyle \mathrm{M}_1$ and $\displaystyle \mathrm{M}_2$ have the following particulars : $$\begin{aligned} & \mathrm{R}_1=5 \Omega, \mathrm{~N}_1=15, \mathrm{~A}_1=3.6 \times 10^{-3} \mathrm{~m}^2, \mathrm{~B}_1=0.25 \mathrm{~T} \\ & \mathrm{R}_2=7 \Omega, \mathrm{~N}_2=21, \mathrm{~A}_2=1.8 \times 10^{-3} \mathrm{~m}^2, \mathrm{~B}_2=0.50 \mathrm{~T} \end{aligned} $$ Assuming that torsional constant of the springs are same for both coils, what will be the ratio of voltage sensitivity of $\displaystyle \mathrm{M}_1$ and $\displaystyle \mathrm{M}_2$ ?