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The MCQs below are drawn from the Physics subject category.
Showing 1301–1310
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1301
Time taken by light from Sun to reach Earth is:
A. 400 seconds
B. 500 seconds
C. 600 seconds
D. 700 seconds
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Correct Option
Explanation
The OCR indicates option B (600 seconds) as the selected choice in the source text.
1302
Who first studied the visible region of hydrogen spectrum?
A. Lyman
B. Brackett
C. Pfund
D. Balmer
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Correct Option
Explanation
Johann Balmer studied the visible spectral lines of hydrogen (the Balmer series), so Balmer is correct.
1303
When an astronaut reaches near the moon, he sends a radio wave of frequency 5000 MHz towards the moon. He finds that the reflected wave from the moon has a frequency 85 kHz more than the real frequency. The velocity of the rocket with respect to the moon is
A. 2.58 km/sec
B. 3.87 km/sec
C. 1.29 km/sec
D. 5.16 km/sec
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Correct Option
Explanation
For reflected radar, Δf ≈ (2v/c)f, so v = (Δf · c)/(2f) = (0.085 MHz · 300000 km/s)/(2·5000 MHz) ≈ 2.58 km/s.
1304
X-rays travel with
A. the speed of 3,500 m s-1
B. the speed of light
C. the speed of sound
D. the speed of 3,000 m s-1
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Correct Option
Explanation
As electromagnetic radiation, X-rays propagate at the speed of light in vacuum.
1305
Electron of 10 keV energy is incident on tungsten material in vacuum, then emitted radiation will be
A. Cathode rays
B. Visible rays
C. X-rays
D. Infrared rays
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Correct Option
Explanation
High-energy electrons striking a metal target produce X-rays (bremsstrahlung and characteristic radiation).
1306
Then the frequency corresponding to this wavelength is:
A. 400 kHz
B. 100 kHz
C. 500 kHz
D. 200 kHz
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Correct Option
Explanation
Frequency f = c/λ = 3×10^8 m/s ÷ 1500 m = 2×10^5 Hz = 200 kHz, so option B is correct.
1307
The phenomenon of Compton's effect proves that light has
A. wave nature
B. particle nature
C. corpuscular nature
D. dual nature
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Correct Option
Explanation
Compton scattering demonstrates that light behaves as particles (photons) carrying momentum, showing particle nature.
1308
Which are different types of emission spectrum?
A. Continuous spectrum
B. Line spectrum
C. Band spectrum
D. All of the above
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Correct Option
Explanation
Emission spectra can appear as continuous, line, or band spectra depending on the source and transitions involved.
1309
Which of the following radiations form part of the electromagnetic spectrum?
A. Beta rays
B. Alpha rays
C. Cathode rays
D. Gamma rays
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Correct Option
Explanation
Gamma rays are electromagnetic radiation; alpha/beta/cathode rays are particulate or electron streams, so D is correct.
1310
Consult page 50 of your text and tick the correct statement: Velocity of x-rays is greater than velocity of light; Velocity of light is less than velocity of radio waves; Velocity of light, x-rays and radio waves is the same; None of above is correct
A. Velocity of light is less than velocity of radio waves
B. Velocity of light, x-rays and radio waves is the same
C. Velocity of x-rays is greater than velocity of light
D. None of above is correct
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Correct Option
Explanation
All electromagnetic waves (x-rays, visible light, radio) travel at the same speed in vacuum, so option C is correct.
