NEET Ray Optics — Set 12

Question 1

In a compound microscope, what role does the eyepiece play in the final image formation?

Accepted Answer

The eyepiece in a compound microscope acts as a magnifying lens, taking the real, inverted image formed by the objective and producing a larger, virtual image for the observer. It enhances the angular size of the intermediate image, making it appear magnified without altering its orientation.

Question 2

A convex lens ($ f = 40 \, \text{cm} $) and a concave lens ($ f = 20 \, \text{cm} $) are in contact. What is the effective focal length?

Accepted Answer

$ f_1 = 40 \, \text{cm} $, $ f_2 = -20 \, \text{cm} $. $ \frac{1}{f} = \frac{1}{f_1} + \frac{1}{f_2} = \frac{1}{40} + \frac{1}{-20} = \frac{1 - 2}{40} = \frac{-1}{40} $. $ f = -40 \, \text{cm} $ (diverging system).

Question 3

In a concave lens, what property of the lens determines the position of the virtual focal point?

Accepted Answer

The virtual focal point of a concave lens is where diverging rays appear to originate when traced backward. This position is determined by the lens’s focal length, which depends on its curvature and refractive index, defining the extent of divergence.

NEET Physics: Ray Optics — Practice Set 12

Q1. In a compound microscope, what role does the eyepiece play in the final image formation?

Q2. A convex lens (\( f = 40 \, \text{cm} \)) and a concave lens (\( f = 20 \, \text{cm} \)) are in contact. What is the effective focal length?

Q3. In a concave lens, what property of the lens determines the position of the virtual focal point?

Q4. In a prism, when light is incident at a very small angle, what is the approximate relationship between deviation and the prism’s properties?

Q5. A ray of light passes from air (\( n = 1 \)) to glass (\( n = 1.62 \)) at an angle of incidence of \( 30^\circ \). What is the angle of refraction?

Q6. In a concave mirror, when the object is placed at the center of curvature, where is the image formed?

Q7. A converging beam meets a convex lens (\( f = 10 \, \text{cm} \)) \( 5 \, \text{cm} \) before the convergence point. What is the new image distance?

Q8. A double convex lens of refractive index \( 1.55 \) has radii of curvature \( 22 \, \text{cm} \) and \( -22 \, \text{cm} \). What is its focal length?

Q9. An object of height \( 3 \, \text{cm} \) is placed \( 15 \, \text{cm} \) from a concave mirror of focal length \( 10 \, \text{cm} \). What is the height of the image?

Q10. An object is placed \( 16 \, \text{cm} \) from a convex mirror of focal length \( 24 \, \text{cm} \). What is the image distance?