Question

A.Light travels through diamond (n=2.4), which is submersed in water (n=1.3). What is the critical angle at which total internal reflection will occur when the light is incident upon the boundary between water and diamond?

	a.	32.8 degrees
	b.	0.54 degrees
	c.	There is no critical angle
	d.	24.6 degrees

B.Light travels through water (n=1.3) and is incident upon diamond (n=2.4), which is submersed in the water. What is the critical angle at which total internal reflection will occur when the light is incident upon the boundary between water and diamond?

	a.	24.6 degrees
	b.	0.54 degrees
	c.	32.8 degrees
	d.	There is no critical angle

Answer 1

1.

Light travels through diamond, which is submersed in water.

Using snell's law:

n1*sin A1 = n2*sin A2

n1 = refrative index of diamond = 2.4

n2 = refractive index of water = 1.3

when A2 = 90 deg, Critical angle will be

n1*sin Ac = n2*sin 90 deg

Ac = arcsin (n2/n1)

Ac = arcsin(1.3/2.4)

Ac = 32.8 deg

Correct option is a.)

2.

now, light travels through water and is incident upon diamond.

So, n2 = refrative index of diamond = 2.4

n1 = refractive index of water = 1.3

A2 = 90 deg, Critical angle will be

n1*sin Ac = n2*sin(90 deg)

sin(Ac)= 2.4/1.3 = 1.85

Since, -1 < Sin(x) < 1

So, there is no Critical angle.

Therefore correct option is d.