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NSEA · Physics

Units and Measurements

SI units, dimensional analysis, error analysis used heavily in astronomy estimation problems.

In the official syllabus: IAPT — Syllabus for National Standard Examination and Indian National Olympiad in Physics, Chemistry, Biology,…, Astronomy syllabus, Part 1: Physics (refers to Physics syllabus), Unit I: Units and Measurements (read 29 Sept 2026).

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3 practice questions on Units and Measurements for NSEA, with answers

Shishya's practice questions, written with AI. Each answer was checked by an automated second pass, not by a person.

  1. 1.What is the SI unit of luminous intensity?

    • (A)Candela
    • (B)Lumen
    • (C)Lux
    • (D)Watt
    Show the answer and solution

    Answer: (A) Candela

    Solution: Candela (cd) is the SI base unit of luminous intensity, measuring the power emitted by a light source in a particular direction.

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  2. 2.The dimensional formula of universal gravitational constant G is [M^a L^b T^c]. What are the values of a, b, and c respectively?

    • (A)-1, 3, -2
    • (B)1, -3, 2
    • (C)-1, 3, 2
    • (D)1, 3, -2
    Show the answer and solution

    Answer: (A) -1, 3, -2

    Solution: From F = Gm₁m₂/r², we get G = Fr²/(m₁m₂). So [G] = [MLT⁻²][L²]/[M²] = [M⁻¹L³T⁻²], giving a = -1, b = 3, c = -2.

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  3. 3.A parsec is defined as the distance at which one astronomical unit subtends an angle of:

    • (A)1 degree
    • (B)1 arcminute
    • (C)1 arcsecond
    • (D)1 milliarcsecond
    Show the answer and solution

    Answer: (C) 1 arcsecond

    Solution: A parsec (parallax arcsecond) is defined as the distance at which 1 AU subtends an angle of 1 arcsecond, equal to approximately 3.26 light years.

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