Optics Important Questions for NEET Physics - 2026

1. Multiple choice questions.

Q1. The focal length of a convex mirror is:

• (a) Positive
• (b) Negative
• (c) Zero
• (d) Infinity

Answer: (a) Positive

Q2. The refractive index of a medium is 1.5. What is the velocity of light in that medium if the velocity of light in vacuum is $3 \times 10^8$ m/s?

• (a) $2.0 \times 10^8$ m/s
• (b) $2.5 \times 10^8$ m/s
• (c) $1.5 \times 10^8$ m/s
• (d) $3.0 \times 10^8$ m/s

Answer: (a) $2.0 \times 10^8$ m/s

Q3. The condition for total internal reflection is satisfied when:

• (a) Light travels from rarer to denser medium
• (b) Angle of incidence is less than critical angle
• (c) Light travels from denser to rarer medium and angle of incidence exceeds critical angle
• (d) None of the above

Answer: (c) Light travels from denser to rarer medium and angle of incidence exceeds critical angle

Q4. The width of the central maximum in a single slit diffraction pattern is:

• (a) Proportional to slit width
• (b) Inversely proportional to slit width
• (c) Both increase together
• (d) Independent of slit width

Answer: (b) Inversely proportional to slit width

Q5. Light from two coherent sources of equal intensity produces interference. The maximum intensity in the interference pattern is:

• (a) Twice the intensity from one source
• (b) Four times the intensity from one source
• (c) Same as intensity from one source
• (d) Zero

Answer: (b) Four times the intensity from one source

2. Very Short Answer (VSA).

Q1. What is the pole of a spherical mirror?

Answer: The pole of a spherical mirror is its geometric center on the mirror’s surface.

Q2. State Brewster’s law.

Answer: Brewster’s law states that the tangent of the polarising angle equals the refractive index of the medium.

Q3. What is meant by magnification in optics?

Answer: Magnification is the ratio of the height of the image to the height of the object formed by a lens or mirror.

Q4. Name the principle used to explain both reflection and refraction of light.

Answer: Huygens’ principle is used to explain both reflection and refraction of light.

Q5. What is a wavefront?

Answer: A wavefront is an imaginary surface representing points of a wave that vibrate in phase.

3. Short Answer Questions.

Q1. Explain total internal reflection with an example.

Answer: Total internal reflection occurs when light passes from a denser to a rarer medium at an angle greater than the critical angle, causing it to reflect entirely within the denser medium. For example, this principle allows optical fibers to transmit light signals over long distances without loss.

Q2. Derive the lens formula.

Answer:

1. Let object distance be $u$, image distance be $v$, and focal length $f$.
2. Applying the sign convention and geometry, we derive: $\frac{1}{f} = \frac{1}{v} - \frac{1}{u}$.

Thus, the lens formula relates $u$, $v$, and $f$ for thin lenses.

Q3. How is the width of the central maximum affected by wavelength in single slit diffraction?

Answer: The width of the central maximum is directly proportional to the wavelength of light. If the wavelength increases, the central maximum becomes wider. Mathematically, width $= \frac{2D\lambda}{a}$, where $D$ is the distance to the screen and $a$ is the slit width.

Q4. What is the function of a collimator in a spectrometer?

Answer: A collimator produces a parallel beam of light by allowing light to pass through a small slit and then a lens system. This ensures that light entering the prism or grating is parallel, providing accurate measurement of angles in a spectrometer.

Q5. Differentiate between reflecting and refracting telescopes.

Answer: Reflecting telescopes use mirrors to gather and focus light, reducing chromatic aberration. Refracting telescopes use lenses, which may introduce chromatic aberration but are simpler to align. Reflectors are widely used in modern astronomy due to their large apertures.

4. True or False Questions.

Q1. In Young’s double-slit experiment, increasing the slit separation decreases the fringe width.

Answer: True

Q2. Brewster’s angle is the angle of incidence at which reflected light is completely polarized.

Answer: True

Q3. The power of a lens increases as its focal length increases.

Answer: False

Q4. For a convex lens, real images are always formed on the same side as the object.

Answer: False

Q5. Polaroids can be used to reduce glare from surfaces like roads and water.

Answer: True

3. Fill in the Blanks Questions.

Q1. The critical angle for total internal reflection depends on the _________ of the two media.

Answer: refractive indices

Q2. For a concave mirror, the focal length is taken as ________ sign according to the sign convention.

Answer: negative

Q3. The condition for sustained interference is that the sources must be ________.

Answer: coherent

Q4. The magnifying power of a compound microscope depends on the focal lengths of the ______ and the ______.

Answer: objective lens, eyepiece

Q5. The plane containing the electric vector of plane-polarized light is called the _______ of polarization.

Answer: plane

Why Optics is Essential for NEET Physics Preparation

Understanding Optics concepts helps students build a strong base for questions in the NEET Physics section. Light reflection, refraction, and wave properties often appear in exams and clear concepts here are key for better problem-solving and quick answers.

On Vedantu, each NEET Optics important question is exam-ready, matching the latest Physics trends. Our friendly explanations help you feel confident, and stepwise answers improve your clarity for both MCQs and numericals.

Practicing these Physics Optics questions ensures you learn quickly and reduce mistakes. Stay motivated with Vedantu’s trusted content, and focus on scoring higher in the competitive NEET exam with key revision for every concept.