SSC CGL Science – Light & Optics – Level 2 · Exam Level · Tier I Sprint

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SSC CGL Science – Light & Optics – Level 2 · Exam Level · Tier I Sprint – 15 questions, subject: General Science. Every question has the correct answer with a one-line explanation; tap "Show Answer". Free practice for TNPSC, UPSC, SSC, Bank and RRB exams – Shanmugam IAS Academy, Coimbatore.

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1.  
The power of a convex lens of focal length 50 cm is:

Correct Answer: A [+2 D]

Explanation:

Answer: +2 D. 100/50 = +2 D.

2.  
The refractive index of a medium is 1.25. The speed of light in it is (c = 3 × 10⁸ m/s):

Correct Answer: B [2.4 × 10⁸ m/s]

Explanation:

Answer: 2.4 × 10⁸ m/s. 3 × 10⁸ / 1.25.

3.  
Two plane mirrors are inclined at 90°. The number of images of an object between them is:

Correct Answer: C [3]

Explanation:

Answer: 3. 360/90 − 1 = 3.

4.  
Match the followingMatch the column:
P. Rainbow Q. Blue sky R. Mirage S. Twinkling of stars
1. Scattering 2. Atmospheric refraction 3. Dispersion and internal reflection 4. Total internal reflection in hot air layers

Correct Answer: D [P-3, Q-1, R-4, S-2]

Explanation:

Each phenomenon with its cause.

5.  
Assertion–ReasonAssertion (A): The Sun is seen about 2 minutes before it actually rises above the horizon.
Reason (R): Sunlight bends (refracts) as it passes through layers of the atmosphere.

Correct Answer: D [Both A and R are true and R explains A]

Explanation:

Atmospheric refraction lifts the image of the Sun – advance sunrise and delayed sunset.

6.  
An object is placed at the centre of curvature of a concave mirror. The image is:

Correct Answer: C [at C, real, inverted and of the same size]

Explanation:

Answer: at C, real, inverted and of the same size. u = 2f → v = 2f, m = −1.

7.  
A person cannot see distant objects clearly but can read a book. The defect and its correction are:

Correct Answer: B [myopia; concave lens]

Explanation:

Answer: myopia; concave lens. Short sight → minus lens.

8.  
Arrange in orderArrange in increasing order of refractive index: diamond, water, ice, crown glass

Correct Answer: A [ice < water < crown glass < diamond]

Explanation:

Ice 1.31 < water 1.33 < crown glass 1.52 < diamond 2.42.

9.  
Two-quantity comparison
Quantity I: critical angle of water (n = 1.33)
Quantity II: critical angle of diamond (n = 2.42)

Correct Answer: A [Quantity I > Quantity II]

Explanation:

sin C = 1/n: about 48.8° against 24.4°.

10.  
True/false countHow many of these use a concave mirror?
I. Torch reflector
II. Shaving mirror
III. Rear-view mirror of a car
IV. Solar cooker

Correct Answer: C [3]

Explanation:

Answer: 3. Rear-view mirrors are convex.

11.  
Diagram-basedParallel rays enter a closed box and come out meeting at a point, as shown. The box most likely contains a:

Correct Answer: D [convex lens]

Explanation:

Light passes through and converges → converging lens.

12.  
A swimming pool 3 m deep (water, n = 4/3) appears, when seen from directly above, to be about:

Correct Answer: A [2.25 m deep]

Explanation:

Answer: 2.25 m deep. 3 × 3/4 = 2.25 m.

13.  
The Sun is visible a little before actual sunrise because of:

Correct Answer: B [atmospheric refraction]

Explanation:

Light bends through the layers of air over the horizon.

14.  
A red rose seen in pure blue light appears:

Correct Answer: D [black]

Explanation:

It absorbs blue and there is no red light to reflect.

15.  
Optical fibres used in endoscopes work on:

Correct Answer: B [total internal reflection]

Explanation:

Light is guided by repeated TIR.

➤ Full notes, shortcuts and every answer explained – SSC CGL 2026 General Science book (₹149): www.shanmugamiasacademy.in/study-materials/ssc-cgl-general-science

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