Question

the angle of refraction in a glass block of refractive index 1.5 is 19°.calculate the angle of incidence.
answer:-29.23

Answer 1

red index = sini/sinr
1.5= sini/sin19
sini= 1.5*sin19
= 1.5*19.48=29.3

Answer 2

from the formula of Snell's law,

úi*sin(i) = úr*sin(r)
where,
úi = refractive index of incident Ray
úr = refractive index of refractive Ray
sin(i) = sine of angle of incidence
sin(r) = sine of angle of refraction

thus,
1*sin(i) = 1.5*sin(19°)
or, sin(i) = 1.5*0.3255
or, sin(i) = 0.4883522
or, i = 29.2322°

Thus the angle of in incidence is 29.2322°