Assertion (A): A convex mirror is used as a rear-view mirror. Reason (R): It gives a wider field of view. MCQ with Answer and Explanation

Assertion (A): A convex mirror is used as a rear-view mirror. Reason (R): It gives a wider field of view.
A. A true, R false
B. Both A and R true, R correct explanation
C. Both A and R true, R not correct explanation
D. A false, R true
Answer: Option B
Solution (By JKSSB Mock Tests)
Convex mirror provides wider field and erect image, so R explains A correctly.

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Practice More Physics Questions

Question #1
A person cannot see objects clearly beyond 2 m. This defect of vision is:
A. Hypermetropia
B. Presbyopia
C. Myopia
D. Astigmatism

Correct Answer: Option C


Explanation:
Myopia (nearsightedness) is the inability to see distant objects clearly, with far point less than infinity. Here, far point is 2 m. Corrected using concave lens. Hypermetropia (farsightedness) affects near vision; presbyopia is age-related loss of accommodation; astigmatism involves uneven corneal curvature. Memory aid: 'Myopia = near-sighted; far point reduced'. This application question tests knowledge of vision defects and corrections, frequently appearing in competitive exams. Always link symptom (blurred distant vision) to defect (myopia) and correction (diverging lens).

This question belongs to: Science Physics
Question #2
The function of a fuse in a domestic circuit is to
A. Regulate voltage
B. Reduce current
C. Protect against short circuit and overload
D. Increase power factor

Correct Answer: Option C


Explanation:
Fuse is a safety device: thin wire melts when current exceeds safe limit due to short circuit or overload, breaking circuit. Prevents fire and appliance damage. Based on heating effect. MCB is modern alternative.

This question belongs to: Science Physics
Question #3
The escape velocity from a planet depends on:
A. Temperature of the planet
B. Mass of the escaping body
C. Radius of the planet only
D. Both mass and radius of the planet

Correct Answer: Option D


Explanation:
Escape velocity v_e = √(2GM/R), where M is planet mass, R its radius. Thus v_e depends on both M and R. It is independent of the escaping body's mass (as gravitational and inertial mass cancel). Memory tip: 'v_e ∝ √(M/R); larger M or smaller R ⇒ higher escape velocity'. This gravitation formula application is frequently tested in competitive exams. Always recall that escape velocity is a property of the planet, not the projectile. This problem assesses understanding of gravitational potential energy concepts.

This question belongs to: Science Physics