electric current and magnetism - Category wise Question and Answer Practice Test with Solutions

Question : 6 [NDA]

Yellow colour light is used as fog light because yellow colour

a) has the longest wavelength among all colours except red and orange but the red colour is already used for brake light and stop light whereas orange colour is avoided due to its similarity with red

b) light is most scattered by fog

c) has the longest wavelength among all colours

d) has the shortest wavelength among all colours not already reserved for other purpose

Question : 7

The magnetism of magnet is due to

a) pressure of big magnet inside the earth

b) the spin motion of electron

c) earth

d) cosmic rays

Question : 8 [UPPCS (Pre) 2009]

In comparison to an electric bulb, a fluorescent tube is preferred because

a) In the tube, electric energy almost converted into light energy

b) It has greater external outer surface to radiate/emit the light

c) There is no effect of voltage fluctuation on it

d) None of the above

Question : 9

When n-p-n transistor is used as an amplifier

a) holes move from emitter to base

b) electrons move from base to collector

c) electrons move from collector to base

d) holes move from base to emitter

Question : 10 [UPPCS (Pre) 2006]

The value of 1 kilowatt hour is

a) $10^3$ J

b) 3.6 × $10^6$ J

c) 3.6 × $10^3$ J

d) $10^5$ J