CUET · PHYSICS · PYQ PAPER 2025

Choose the correct relation between focal length f and radius of curvature R of a convex mirror from the following:

A f = +R
B f = -R
C f = -0.5 R
D f = +0.5 R

Verified Solution

Answer & Solution

Correct Answer

(D) f = +0.5 R

Step-by-step Solution

Detailed explanation

For a spherical mirror with a small aperture, the focal length is exactly half of its radius of curvature, expressed as \(f=R / 2\) or \(f=0.5 R\). According to the Cartesian sign convention, the focal length and radius of curvature for a convex mirror are always taken as…

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

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Match List-I with List-II

List-I (Types of solutions)	List-II (Examples)
(A) Gas in Gas solution	(I) Oxygen dissolved in water
(B) Gas in Liquid solution	(II) Copper dissolved in gold
(C) Liquid in Solid solution	(III) Mixture of oxygen and nitrogen gases
(D) Solid in Solid solution	(IV) Amalgam of mercury with sodium

Choose the correct answer from the options given below:

CUET 2025 Hard

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List-I (Materials)	List-II (Band Gap (eV))
(A) Germanium	(I) 1.42 eV
(B) Gallium Arsenide	(II) > 3 eV
(C) Insulator	(III) 1.1 eV
(D) Silicon	(IV) 0.7 eV

X = x	P(X = x)
0	\(\frac{1}{4}\)
1	\(\frac{1}{2}\)
2	\(\frac{1}{4}\)