Critical Angle

Q.

A ray of light from a denser medium strikes a rarer medium at angle of incidence $i$ as shown in the figure. The reflected and refracted rays make an angle of ${90}^{\circ }$ with each other. The angles of reflection and refraction are $r$ and $r^{\prime }$ respectively. The critical angle is

1. ${\sin }^{-1}\left(\tan r\right)$

2. ${\sin }^{-1}\left(\tan i\right)$

3. ${\sin }^{-1}\left(\tan r^{\prime }\right)$

4. ${\tan }^{-1}\left(\tan i\right)$

Q.

The wavelength of light in two liquids $x$ and $y$ is $3500A^{\circ }$ and $7000A^{\circ }$, then the critical angle of $x$ relative to $y$ will be______.

1. ${60}^{\circ }$

2. ${45}^{\circ }$

3. ${30}^{\circ }$

4. ${15}^{\circ }$

Q. A straight line graph is obtained by plotting sine of angle of incidence versus sine of angle of refraction. The slope of this graph represents :

1. Gravitational
2. None of these
3. Velocity of light
4. Refractive index