NEET Prep

Optics

27 NEET questions on Optics. A sample is shown below with full explanations; the rest are available free after signing up.

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Q1.A microscope has an objective of focal length 2 cm, eyepiece of focal length 4 cm and the tube length of 40 cm. If the distance of distinct vision of eye is 25 cm, the magnification in the microscope is

  • A100
  • B125Answer
  • C150
  • D250

Explanation

For a compound microscope with the final image at the near point, M = (L/f_o) x (D/f_e), where L is the tube length. Substituting L = 40 cm, f_o = 2 cm, D = 25 cm and f_e = 4 cm gives M = 20 x 6.25 = 125.

Source: NEET 2025 (4 May), Code 45, Q2

Optics2025easy

Q2.In a certain camera, a combination of four similar thin convex lenses are arranged axially in contact. Then the power of the combination and the total magnification in comparison to the power (p) and magnification (m) for each lens will be, respectively

  • A4p and 4m
  • Bp⁴ and 4m
  • C4p and m⁴Answer
  • Dp⁴ and m⁴

Explanation

Powers of thin lenses in contact add algebraically, so the combination has power 4p. Magnifications behave differently: each lens magnifies the image formed by the one before it, so the magnifications multiply to give m⁴.

Source: NEET 2025 (4 May), Code 45, Q13

Optics2025medium

Q3.An unpolarized light beam travelling in air is incident on a medium of refractive index 1.73 at Brewster's angle. Then

  • AReflected light is completely polarized and the angle of reflection is close to 60°Answer
  • BReflected light is partially polarized and the angle of reflection is close to 30°
  • CBoth reflected and transmitted light are perfectly polarized with angles of reflection and refraction close to 60° and 30°, respectively
  • DTransmitted light is completely polarized with angle of refraction close to 30°

Explanation

Brewster's law gives tan θp = μ = 1.73 ≈ √3, so θp = 60°, and the angle of reflection equals the angle of incidence. At this angle the reflected beam is completely plane-polarised while the transmitted beam is only partially polarised — which is what rules out options C and D.

Source: NEET 2025 (4 May), Code 45, Q27

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