Wavelength measurement instrument: MCQ with Answer and Explanation

Wavelength measurement instrument:
A. Telescope
B. Spectrometer
C. Microscope
D. Galvanometer
Answer: Option B
Solution (By JKExamLibrary)
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
A current of 2 A flows through a 10 Ω resistor for 1 minute. Heat produced is
A. 2400 J
B. 400 J
C. 20 J
D. 1200 J

Correct Answer: Option A


Explanation:
H = I² R t = 4 × 10 × 60 = 2400 J.

This question belongs to: Science Physics
Question #2
Raindrops fall to the ground with a uniform, constant velocity. This constant velocity is achieved when the gravitational pull is perfectly balanced by:
A. The sum of viscous drag force and buoyant force
B. Viscous drag force alone
C. Buoyant force alone
D. Surface tension of the drop

Correct Answer: Option A


Explanation:
As a raindrop falls, it accelerates due to gravity. The upward viscous drag force of the air increases with the drop's velocity (Stokes' Law). Eventually, the downward weight of the drop is exactly balanced by the upward buoyant force of the air plus the upward viscous drag force. The net force becomes zero, and it falls with a constant 'terminal velocity'.

This question belongs to: Science Physics
Question #3
The angle of incidence is equal to angle of reflection is the law of
A. Reflection
B. Refraction
C. Diffraction
D. Dispersion

Correct Answer: Option A


Explanation:
Law of reflection.

This question belongs to: Science Physics