NEET (UG)

Practice Test 1 — Ray Optics & Optical Instruments

12 questions • 18 minutes • auto-graded with full solutions

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Section A — MCQ (Single Correct)

Question 1

The focal length of a concave mirror is half its:

Solution: $f = R/2$.

Question 2

A convex mirror always forms an image that is:

Solution: Convex mirror: virtual, erect, diminished.

Question 3

Snell's law relates the angles through the:

Solution: $n_1\sin\theta_1 = n_2\sin\theta_2$.

Question 4

The critical angle for $n = 1.5$ is given by:

Solution: $\sin\theta_c = 1/n = 1/1.5$.

Question 5

The lens formula is:

Solution: $1/f = 1/v - 1/u$.

Question 6

Two lenses of power $+2\ \text{D}$ and $+3\ \text{D}$ in contact give:

Solution: $P = P_1 + P_2 = 5\ \text{D}$.

Question 7

In a prism, the colour that deviates most is:

Solution: Violet has the highest index, so deviates most.

Question 8

The magnifying power of a telescope is:

Solution: $M = f_o/f_e$.

Section B — Assertion & Reason

Question 9

A: A convex mirror is used as a rear-view mirror in vehicles.
R: A convex mirror always forms an erect, diminished image and has a wide field of view.

Solution: The wide field of view from its erect, diminished image is exactly why it is used — R explains A.

Question 10

A: Optical fibres can transmit light over long distances with little loss.
R: Light travels along the fibre core by repeated total internal reflection.

Solution: TIR keeps the light confined within the core — R explains A.

Question 11

A: A concave lens is used to correct hypermetropia (long-sightedness).
R: Hypermetropia occurs when the image of a near object forms behind the retina.

Solution: Hypermetropia is corrected with a convex lens, so A is false; the cause given in R is correct.

Question 12

A: A prism splits white light into its component colours.
R: The refractive index of the prism material varies with the wavelength of light.

Solution: Index varying with wavelength causes different colours to deviate differently — R explains A.