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Total internal reflection is the phenomenon of reflection of light into denser medium at the interface of denser medium with a rarer medium. For this phenomenon to occur necessary condition is that light must travel from denser to rarer and angle of incidence in denser medium must be greater than critical angle (C) for the pair of media in contact. Critical angle depends on nature of medium and wavelength of tight. We can show that $\mu=\frac{1}{\sin\text{C}}.$

1. Critical angle for glass air interface, where ft of glass is $\frac{3}{2}$ is,

1. 41.8
2. 60º
3. 30º
4. 15º

2. Critical angle for water air interface is 48.6º. What is the refractive index of water?

1. $1$
2. $\frac{3}{2}$
3. $\frac{4}{3}$
4. $\frac{3}{4}$

3. Critical angle for air water interface for violet colour is 49º. Its value for red colour would be:

1. 49º
2. 50º
3. 48º
4. Cannot say.

4. Which of the following is not due to total internal reflection?

1. Working of optical fibre.
2. Difference between apparent and real depth of a pond.
3. Mirage on hot summer days.
4. Brilliance of diamond.

5. Critical angle of glass is $\theta_1$ and that of water is $\theta_2$The critical angle for water and glass surface would be $(\mu_\text{g}=\frac{3}{2},\ \mu_\text{w}=\frac{4}{3})$

1. Less than $\theta_2$
2. Between $\theta_1$ and $\theta_2$
3. Greater than $\theta_2$
4. Less than $\theta_1$