The dimensional formula of Planck's constant is identical to that of: MCQ with Answer and Explanation

The dimensional formula of Planck's constant is identical to that of:
A. Angular momentum
B. Torque
C. Linear momentum
D. Force
Answer: Option A
Solution (By JKSSB Mock Tests)
Planck's constant (h) has dimensions [ML²T⁻¹]. Angular momentum (L = mvr) has dimensions [M][LT⁻¹][L] = [ML²T⁻¹], matching exactly. Linear momentum is [MLT⁻¹], force is [MLT⁻²], and torque is [ML²T⁻²]. This dimensional equivalence is fundamental in quantum mechanics, linking wave-particle duality. Memory tip: Both represent 'action' quantities with identical dimensional structure. This concept frequently appears in competitive exams testing dimensional analysis skills.

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Practice More Physics Questions

Question #1
The angle of incidence for a light ray is 30°. According to laws of reflection, angle of reflection is
A. 60°
B. 30°
C. 90°
D. 15°

Correct Answer: Option B


Explanation:
Law of reflection: angle of incidence = angle of reflection, both measured from normal. So 30°. If angle with mirror is given, convert to normal. Always equal for smooth surfaces.

This question belongs to: Science Physics
Question #2
A Wheatstone bridge is said to be completely balanced when:
A. Current through the galvanometer is maximum.
B. Potential difference across the galvanometer is zero.
C. All four resistors have exactly identical values.
D. The battery supplies zero current.

Correct Answer: Option B


Explanation:
A Wheatstone bridge circuit consists of four arms with resistances P, Q, R, S and a galvanometer in the middle. It is balanced when no current flows through the galvanometer arm. This happens exclusively when the potentials at the two ends of the galvanometer are equal, meaning the potential difference across it is exactly zero (P/Q = R/S).

This question belongs to: Science Physics
Question #3
The phenomenon of total internal reflection is used in:
A. Diamond cutting
B. Optical fibers
C. Neither
D. Both (a) and (b)

Correct Answer: Option D


Explanation:
Total internal reflection (TIR) is exploited in optical fibers for light transmission with minimal loss (core-cladding interface). In diamonds, high refractive index (n≈2.4) gives small critical angle (~24°), so most light undergoes TIR, enhancing brilliance through multiple reflections. Memory aid: 'TIR applications: optical fibers (communication), diamonds (sparkle), prisms (binoculars)'. This application question tests optics uses, frequently appearing in competitive exams. Always link physical principles to technological applications; competitive exams emphasize practical relevance of theoretical concepts.

This question belongs to: Science Physics