Q. Light from the Sun reaches us in nearly
A.2 minutes
B.4 minutes
C.8 minutes
D.16 minutes
Q. Stars appears to move from east to west because
A.all stars move from east to west
B.the earth rotates from west to east
C.the earth rotates from east to west
D.the background of the stars moves from west to east
Q. Planets do not twinkle because
A.they emit light of a constant intensity
B.their distance from the earth does not change with time
C.they are very far away from the earth resulting in decrease in intensity of light
D.they are nearer to earth and hence we receive a greater amount of light and, therefore minor variations in the intensity are not noticeable
Q. Metals are good conductors of electricity because
A.they contain free electrons
B.the atoms are lightly packed
C.they have high melting point
D.All of the above
Q. Rectifiers are used to convert
A.Direct current to Alternating current
B.Alternating current to Direct current
C.high voltage to low voltage
D.low voltage to high voltage
Q. out of the following, which is not emitted by radioactive substance?
A.Electrons
B.Electromagnetic radiations
C.Alpha particles
D.Neutrons
Q. Sound waves in air are
A.transverse
B.longitudinal
C.electromagnetic
D.polarised
Q. Magnetism at the centre of a bar magnet is
A.minimum
B.maximum
C.zero
D.minimum or maximum
Q. Find the maximum velocity for the overturn of a car moving on a circular track of radius 100 m. The co-efficient of friction between the road and tyre is 0.2
A.0.14 m/s
B.140 m/s
C.1.4 km/s
D.14 m/s
Q. Of the following properties of a wave, the one that is independent of the other is its
A.amplitude
B.velocity
C.wavelength
D.frequency
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