For a telescope, larger be the diameter of the objective lens:

• greater the resolving power

• smaller is the resolving power

• greater is the magnifying power

• smaller is the magnifying power

If the critical angle for total internal reflection from a medium to vacuum is 30°, the velocity of light in the medium is :

• 3 × 10⁸ m/s

• 1.5 × 10⁸ m/s

• 6 × 10⁸ m/s

• $\sqrt{3}$ × 10⁸ m/s

The deviation is maximum for which colour :

• Violet

• Red

• Blue

• Green

A prism of refractive index √2 has a refracting angle of 60°. At what angle a ray must be incident on it so that it suffers a minimum deviation?

• 45°

• 60°

• 90°

• 180°

A transparent cube of 15 cm edge contains a small air bubble. Its apparent depth, when viewed through one face, is 6 cm and when viewed through the opposite face is 4 cm. Then the refractive index of the material of the cube is:

• 2.0

• 2.5

• 1.6

• 1.5

The radius of the convex surface of the plano-convex lens is 20 cm and the refractive index of the material of the lens is 1.5. The focal length is :

• 30 cm

• 50 cm

• 20 cm

• 40 cm

The refractive index of the material of the prism and liquid are 1.56 and 1.32 respectively. What will be the value of θ for the following refraction?

• $\mathrm{sin\theta } \ge \frac{13}{11}$

• $\mathrm{sin\theta } \ge \frac{11}{13}$

• $\mathrm{sin\theta } \ge \frac{\sqrt{3}}{2}$

• $\mathrm{sin\theta } \ge \frac{1}{\sqrt{2}}$

148.

A person who can see things most clearly at a distance of 10 cm, requires spectacles to enable to see clearly things at a distance of 30 cm. What should be the focal length of the spectacles?

• 15 cm (concave)

• 15 cm (convex)

• 10 cm (concave)

• 0

In the given figure, what is the angle of the prism?

• A

• B

• C

• D

 A light wave travels from glass to water. The refractive indices for glass and water are $\frac{3}{2}$ and $\frac{4}{3}$ respectively. The value of the critical angle will be :

• ${\sin }^{-1}\left(\frac{1}{2}\right)$

• ${\sin }^{-1}\left(\frac{9}{8}\right)$

• ${\sin }^{-1}\left(\frac{8}{9}\right)$

• ${\sin }^{-1}\left(\frac{5}{7}\right)$