Two moving coil meters $M_1$ and $M_2$ having the following particulars .$R_1=10\Omega ,N_1=30, A_1= 3.6 \times 10^{-3}m^2,B_1=0.25 \;T,R_2=14\Omega ,N_2=42, A_2= 1.8 \times 10^{-3}m^2,B_2=0.50 \;T$ The spring constant are identical for the two meters . Determine the ratio of voltage sensitivity of $M_2$ and $M_1$
