Wavelength measurement instrument: MCQ with Answer and Explanation

Wavelength measurement instrument:
A. Microscope
B. Galvanometer
C. Spectrometer
D. Telescope
Answer: Option C
Solution (By JKSSB Mock Tests)
Spectrometer uses diffraction grating/prism to disperse light and measure wavelengths via angular positions. Memory tip: 'Spectrometer = wavelength via dispersion; used in spectroscopy'. Instrument application frequently tested in competitive exams.

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Practice More Physics Questions

Question #1
The half-life of a radioactive sample is 3 days. After 9 days, fraction remaining is
A. 1/8
B. 1/2
C. 1/4
D. 1/16

Correct Answer: Option A


Explanation:
3 half-lives (9/3=3) => (1/2)³ = 1/8.

This question belongs to: Science Physics
Question #2
One astronomical unit (AU) is the
A. Distance travelled by light in one year
B. Distance between Earth and Moon
C. Distance between Earth and Sun
D. Radius of Earth

Correct Answer: Option C


Explanation:
1 AU ≈ 1.5 × 10⁸ km, average Earth-Sun distance.

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Question #3
The unit of power, watt, is equivalent to
A. J s
B. N m
C. N/s
D. J/s

Correct Answer: Option D


Explanation:
Watt = joule per second.

This question belongs to: Science Physics