Concave mirror forms real image when object is placed: MCQ with Answer and Explanation

Concave mirror forms real image when object is placed:
A. At focus
B. Between pole and focus
C. At pole
D. Beyond focus
Answer: Option D
Solution (By JKSSB Mock Tests)
Concave mirror: real, inverted image forms when object beyond focal point (u > f). Between pole and focus: virtual, erect image. At focus: image at infinity. Memory aid: 'Concave: object beyond F ⇒ real image; within F ⇒ virtual'. Ray optics concept frequently tested to verify mirror image formation understanding in competitive exams.

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Practice More Physics Questions

Question #1
The concept of 'Inertia' was first practically developed by which scientist before Newton incorporated it into his First Law?
A. Galileo Galilei
B. Archimedes
C. Aristotle
D. Johannes Kepler

Correct Answer: Option A


Explanation:
Galileo Galilei conducted experiments rolling balls down inclined planes and concluded that an object in motion would continue moving indefinitely on a frictionless surface. This completely challenged Aristotelian mechanics and formulated the concept of inertia, which Isaac Newton later formalized as his First Law of Motion.

This question belongs to: Science Physics
Question #2
Assertion (A): Gamma rays are fundamentally un-deflected by electric and magnetic fields. Reason (R): Gamma rays carry no electrical charge.
A. Both A and R are true but R is NOT the correct explanation of A.
B. A is true but R is false.
C. A is false but R is true.
D. Both A and R are true and R is the correct explanation of A.

Correct Answer: Option D


Explanation:
Electric fields deflect charged particles via Coulomb forces (F=qE), and magnetic fields deflect moving charged particles via Lorentz forces (F=qvB). Gamma rays are purely high-energy electromagnetic photons. Because they lack any electrical charge (q=0), both electric and magnetic forces on them are exactly zero. Therefore, they pass through fields completely un-deflected. R explains A perfectly.

This question belongs to: Science Physics
Question #3
The speed of sound in air at 20°C is approximately
A. 300 m/s
B. 360 m/s
C. 343 m/s
D. 330 m/s

Correct Answer: Option C


Explanation:
At 0°C ≈ 331 m/s, increases with temperature. At 20°C ≈ 343 m/s.

This question belongs to: Science Physics