1.  Difference between apparent and real depth of the pond

2.  Mirage on hot summer days

3.  Brilliance of the diamond

4.  Working of optical fibre

A ray of light travelling in a transparent medium of refractive index $\mu$ falls on a surface separating the medium from the air at an angle of incidence of 45 °. For which of the following value of $\mu$, the ray can undergo total internal reflection?

1. $\mu =1.33$

2. $\mu =1.40$

3. $\mu =1.50$

4. $\mu =1.25$

The speed of light in media M₁ and M₂ is 1.5 × 10⁸ m/s and 2.0 × 10⁸ m/s respectively. A ray of light enters from medium M₁ to M₂ at an incidence angle i. If the ray suffers total internal reflection, the value of i is -

1. Equal to or less than sin^–1 $\left(\frac{3}{5}\right)$

2. Equal to or greater than sin^–1 $\left(\frac{3}{4}\right)$

3. less than sin^–1$\left(\frac{2}{3}\right)$

4. Equal to sin^–1 $\left(\frac{2}{3}\right)$

A small coin is resting on the bottom of a beaker filled with a liquid. A ray of light from the coin travels upto the surface of the liquid and moves along its surface (see figure). 
                
How fast is the light traveling in the liquid?

1. $1.8\times {10}^8 m/s$

2. $2.4\times {10}^8 m/s$

3. $3.0\times {10}^8 m/s$

4. $1.2\times {10}^8 m/s$