In a moving coil galvanometer, two moving coils \( M_{1} \) and \( M_{2} \) have the following particulars:
\( R_{1} = 5 \, \Omega, \ N_{1} = 15, \ A_{1} = 3.6 \times 10^{-3} \, \text{m}^{2}, \ B_{1} = 0.25 \, \text{T} \)
\( R_{2} = 7 \, \Omega, \ N_{2} = 21, \ A_{2} = 1.8 \times 10^{-3} \, \text{m}^{2}, \ B_{2} = 0.50 \, \text{T} \)
Assuming that torsional constant of the springs are same for both coils, what will be the ratio of voltage sensitivity of \( M_{1} \) and \( M_{2} \)?