Refractive index of air w.r.to glass, gηa = 1.50
Refractive index of air w.r.to water, wηa = 133
Therefore,
aηg x gηw x wηa= 1
1/1.50 xgηw 1.33 = 1
gηw = 1.50/ 1.33 = 1.13
gηw = 1/sin C
Sin C = l/gηw
= 1/1.13
= 0.88
C = 1.08° , is the critical angle.
Calculate dispersive power of glass, accurately up to decimal places, from the following data:
Refractive index of glass for red colour = 1.60
Refractive index of glass for yellow colour =1.61
Refractive index of glass for violet colour = 1.62