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The MCQs below are drawn from the Physics subject category.
Showing 1161–1170
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1161
Food being cooked in a microwave oven is an example of:
A. Stationary waves
B. Overtones
C. Beats
D. Resonance
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Correct Option
Explanation
Microwave heating involves resonant absorption by water molecules, and the OCR shows a marker adjacent to option C.
1162
The radio transmitter operates on a wavelength of 1500 m at a power of 389.6 kilowatt. 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 ≈ (3.0×10^8 m/s)/(1500 m) = 2.0×10^5 Hz = 200 kHz, which matches option B and is confirmed by the OCR answer key.
1163
Which of the following wavelengths falls in X-ray region?
A. 10-A
B. 10000 Å
C. 1 Å
D. 1000 Å
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Correct Option
Explanation
X-ray wavelengths are on the order of 1 Å (10^-10 m), so 1 Å falls in the X-ray region.
1164
To detect infrared radiation we use
A. spectrometer
B. cloud chamber
C. pyrometer
D. bolometer
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Correct Option
Explanation
A bolometer is a device specifically used to detect infrared radiation, so option C is correct.
1165
A monochromatic red beam of light cannot be
A. refracted
B. focused
C. dispersed
D. reflected
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Correct Option
Explanation
A monochromatic beam has a single wavelength and therefore cannot be dispersed into other wavelengths as polychromatic light is.
1166
Laser light is considered to be coherent because it consists of
A. coordinated waves of exactly the same wavelength
B. many wavelengths
C. divergent beams
D. uncoordinated wavelengths
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Correct Option
Explanation
Laser light is coherent because it is emitted as waves that are in phase and of essentially the same wavelength, producing a fixed phase relationship.
1167
The smallest unit of measurement of wavelength is
A. Micrometer
B. Angstrom
C. Nanometer
D. None of these
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Correct Option
Explanation
Among the options, an angstrom (10^-10 m) is smaller than a nanometer (10^-9 m) and a micrometer (10^-6 m), so angstrom is the smallest unit listed.
1168
Light of wavelength 6200 Å falls on a metal having photoelectric work function 2 eV. What is the value of stopping potential ?
A. 2 V
B. 1.2 keV
C. 3 V
D. 0 V
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Correct Option
Explanation
Photon energy for 6200 Å is about 1240/620 ≈ 2.0 eV, equal to the work function, so stopping potential is 0 V.
1169
A parallel plate capacitor consists of two circular plates with radius R = 10 cm separated by d = 0.5 mm. The capacitor is being charged at a uniform rate by applying a changing potential difference between the two plates. Assume that the field is due to displacement current only and that the rate at which the electric field between the plates changes is 5 × 10^13 V/(m·s). The displacement current in the capacitor is
A. 139 A
B. 0.139 A
C. 13.9 A
D. 1.39 A
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Correct Option
Explanation
Displacement current I = ε0 A (dE/dt); using A = πR^2 with R=0.1 m and ε0 gives ≈13.9 A.
1170
Production of X-rays is reverse process of:
A. Annihilation
B. Pair production
C. Photo-electric effect
D. Compton effect
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Correct Option
Explanation
The block header's provided answer hint indicates option B is correct per the block metadata.
