The difference of speed of light in the two media A and \( (v_A - v_B) \) is \( 2.6 \times 10^7 \, \text{m /s}^{} \). If the refractive index of medium B is \( 1.47 \), then the ratio of refractive index of medium B to medium A is: (Given : speed of light in vacuum \( c = 3 \times 10^8 \, \text{m s}^{-1} \) )