25.
Lux is the SI unit of
A. intensity of illumination
B. luminous efficiency
C. luminous flux
D. luminous intensity
Answer & Explanation
Answer: Option A
Explanation:
The SI unit of intensity of illumination (illuminance) is the lux. An illuminance of 1.0 lux is produced by 1.0 lumen of light shining on an area of 1.0 m^2.
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26.
On a rainy day, small oil films on water show brilliant colours. This is due to
A. dispersion B. interference
C. diffraction D. polarization
Answer & Explanation
Answer: Option B
Explanation:
No answer description available for this question. Let us discuss.
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27.
Point A is at a lower electrical potential than point B. An electron between them on the line joining them will
A. move towards A
B. move towards B
C. move at right angles to the line joining A and B
D. remain at rest
Answer & Explanation
Answer: Option B
Explanation:
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28.
Materials for rain-proof coats and tents owe their water-proof properties to
A. surface tension
B. viscosity
C. specific gravity
D. elasticity
Answer & Explanation
Answer: Option A
Explanation:
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29.
RADAR is used for
A. locating submerged submarines
B. receiving a signals in a radio receiver
C. locating geostationary satellites
D. detecting and locating the position of objects such as aeroplanes
Answer & Explanation
Answer: Option D
Explanation:
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30.
Sound of frequency below 20 Hz is called
A. audio sounds
B. infrasonic
C. ultrasonic
D. supersonics
Answer & Explanation
Answer: Option B
Explanation:
No answer description available for this question.