Lighting and Magnetic Effects of Current NDA Questions

NDA Physics

Lighting and Magnetic Effects of Current MCQ Questions


7.
In an electric motor, the energy transformation is
A.
From electrical to chemical
B.
From chemical to light
C.
From mechanical to electrical
D.
From electrical to mechanical
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ANSWER :
D. From electrical to mechanical
8.
Which of the following statements is incorrect regarding magnetic field lines?
A.
The direction of the magnetic field at a point is taken to be the direction in which the north pole of a magnetic compass needle points.
B.
Magnetic field lines are closed curves.
C.
If magnetic field lines are parallel and equidistant, they represent zero field strength
D.
Relative strength of the magnetic field is shown by the degree of closeness of the field lines.
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ANSWER :
C. If magnetic field lines are parallel and equidistant, they represent zero field strength
9.
What is the unit of luminous intensity?
A.
Lumen
B.
Lux
C.
Candela
D.
Watt
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ANSWER :
C. Candela
10.
What is the measure of the total amount of visible light emitted by a source?
A.
Lux
B.
Lumen
C.
Watt
D.
Candela
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ANSWER :
B. Lumen
11.
Which gas is commonly used in fluorescent tubes?
A.
Argon
B.
Neon
C.
Mercury Vapor
D.
Helium
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ANSWER :
C. Mercury Vapor
12.
What is the typical efficiency range of LED lights?
A.
50-60%
B.
60-70%
C.
70-80%
D.
80-90%
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ANSWER :
D. 80-90%