Electromagnetic Spectrum(Radio Waves, Microwaves, Infrared, Visible, Ultraviolet. X-rays. Gamma Rays) NEET Questions

Physics - Electromagnetic Waves

Electromagnetic Spectrum(Radio Waves, Microwaves, Infrared, Visible, Ultraviolet. X-rays. Gamma Rays) MCQ Questions


7.
The energy of a photon of an electromagnetic wave is given by:
A.
E = mc²/ν
B.
E = hc²/λ
C.
E = hν = hc/λ, where h = Planck's constant = 6.626×10⁻³⁴ J·s
D.
E = hλ
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ANSWER :
C. E = hν = hc/λ, where h = Planck's constant = 6.626×10⁻³⁴ J·s
8.
Which property of EM waves is responsible for their ability to cause ionisation?
A.
Transverse nature of the wave
B.
High amplitude (intensity)
C.
High photon energy (E = hν) — waves with frequencies above ~10¹⁵ Hz (UV, X-rays, gamma rays) have sufficient energy per photon (>1 eV) to eject electrons from atoms
D.
High wavelength
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ANSWER :
C. High photon energy (E = hν) — waves with frequencies above ~10¹⁵ Hz (UV, X-rays, gamma rays) have sufficient energy per photon (>1 eV) to eject electrons from atoms
9.
Electromagnetic waves carry energy as well as momentum. The radiation pressure (P) exerted by an EM wave is:
A.
P = c/I
B.
P = I²/c²
C.
P = I/c for total absorption (where I = intensity in W/m²) and P = 2I/c for total reflection
D.
P = I×c
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ANSWER :
C. P = I/c for total absorption (where I = intensity in W/m²) and P = 2I/c for total reflection
10.
Maxwell predicted the existence of electromagnetic waves. The source of EM waves according to Maxwell's theory is:
A.
Only nuclear reactions and radioactive decay
B.
Static charges at high voltage
C.
Oscillating (accelerating) electric charges — accelerating charges produce oscillating electric and magnetic fields that propagate as EM waves
D.
Only permanent magnets in motion
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ANSWER :
C. Oscillating (accelerating) electric charges — accelerating charges produce oscillating electric and magnetic fields that propagate as EM waves
11.
The wavelength range of RADIO WAVES is approximately:
A.
10⁻¹² m to 10⁻¹⁰ m (same as gamma rays)
B.
10⁻⁹ m to 10⁻⁶ m (same as X-rays/UV)
C.
From about 1 mm to 10⁴ km (10⁻³ m to 10⁷ m) — they have the LONGEST wavelengths in the EM spectrum
D.
10⁻⁷ m to 10⁻⁴ m (same as UV/visible)
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ANSWER :
C. From about 1 mm to 10⁴ km (10⁻³ m to 10⁷ m) — they have the LONGEST wavelengths in the EM spectrum
12.
Radio waves are produced by:
A.
Radioactive decay of heavy elements
B.
Oscillating electric charges in antennas (accelerating electrons in conducting wires driven by electronic oscillator circuits)
C.
Thermal radiation from hot bodies at room temperature
D.
Nuclear fission reactions in power plants
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ANSWER :
B. Oscillating electric charges in antennas (accelerating electrons in conducting wires driven by electronic oscillator circuits)