Question

Some transparent substance has refractive index 1.9. Find the critical angle for the border the substance-air. Calculate to one decimal.

Answer 1

Using Snell's law:

n1*sin A1 = n2*sin A2

A1 = Angle of incidence = Critical Angle = = ?

A2 = Angle of refraction = 90 deg (for critical angles)

n1 = refractive index of substance = 1.9

n2 = refractive index of air = 1

So,

1.9*sin = 1*sin 90 deg

sin = 1/1.9

= arcsin (1/1.9) = 31.75686 deg

So, In one decimal:

= Critical angle = 31.8 deg

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