A disc is placed on the surface of the pond which has a refractive index \(5/3.\) A source of light is placed \(4~\text m\) below the surface of liquid. The minimum radius of the disc needed so that light is not coming out is:
1. \(\infty\)
2. \(3~\text m\) 
3. \(6~\text m\) 
4. \(4~\text m\) 
Subtopic:  Refraction at Curved Surface |
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A point object is moving at a speed of \(8~\text{cm/s}\) in front of a converging lens along the principal axis, as shown in the figure. At this moment, the speed of the image is:
1. \(32~\text{cm/s}\) 2. \(34~\text{cm/s}\)
3. \(20~\text{cm/s}\) 4. \(10~\text{cm/s}\)
Subtopic:  Refraction at Curved Surface |
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In the given diagram image forms at a distance of \(15~\text{cm}\) inside the medium of refractive index \(1.5.\) Find the object distance (in \(\text{cm}\)) from point \(P.\)
     

1. 15
2. 30
3. 12
4. 10
Subtopic:  Refraction at Curved Surface |
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A light ray enters a solid glass sphere of refractive index \(\mu=\sqrt{3}\) at an angle of incidence \(60^\circ\). The ray is both reflected and refracted at the farther surface of the sphere. The angle (in degrees) between the reflected and refracted rays at this surface is:
1. \(30\)
2. \(60\)
3. \(90\)
4. \(180\)

Subtopic:  Refraction at Curved Surface |
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