Ray Optics and Optical Instruments

In a compound microscope, the intermediate image is

• virtual, erect and magnified

• real, erect and magnified

• real, inverted and magnified

• virtual, erect and reduced

A ray of light passes through an equilateral prism such that an angle of incidence is equal to the angle of emergence and the latter is equal to $\frac{3}{4}$th the angle of prism. The angle of deviation is

• 45°

• 39°

• 20°

• 30°

Time taken by sunlight to pass through a window of thickness 4 mm whose refractive index is $\frac{3}{2}$ is

• 2 × 10^-4 s

• 2 × 10⁴ s

• 2 × 10^-11 s

• 2 × 10¹¹ s

Two thin lenses of focal length 20 cm and 25 cm are in contact. The effective power of the combination is

• 4.5 D

• 18 D

• 45 D

• 9 D

The magnification of the image when an object is placed at a distance x from the principal focus of a mirror of focal length f is

• $\frac{\mathrm{x}}{\mathrm{f}}$

• $1 + \frac{\mathrm{f}}{\mathrm{x}}$

• $\frac{\mathrm{f}}{\mathrm{x}}$

• $1 - \frac{\mathrm{f}}{\mathrm{x}}$

If n₁ and n₂ are the refractive indices of the core and the cladding respectively of an optic fibre, then

• n₁ = n₂

• n₁ < n₂

• n₂ < n₁

• n₂ = 2 n₁

The refractive indices of glass and quartz w.r.t. air are 3/2 and 12/5 respectively. The refractive index of quartz w.r.t. glass is

• 8/5

• 5/8

• 5/18

• 18/5

The radius of curvature of concave mirror is 24 cm and the image is magnified by 1.5 times. The object distance is

• 20 cm

• 8 cm

• 16 cm

• 24 cm

A point source of light is kept at a depth of h in water of refractive index 4/ 3. The radius of the circle at the surface of water through which light emits is

• $\frac{3}{\sqrt{7}} \mathrm{h}$

• $\frac{\sqrt{7}}{3} \mathrm{h}$

• $\frac{\sqrt{3}}{7} \mathrm{h}$

• $\frac{7}{\sqrt{3}} \mathrm{h}$

The distance between an object and a divergent lens is m times the focal length of the lens. The linear magnification produced by the lens is

• m

• $\frac{1}{\mathrm{m}}$

• m + 1

• $\frac{1}{\mathrm{m} + 1}$