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IIT-JEE SCREENING - 2004
PHYSICS
29. A block P of mass m is placed on a
horizontal frictionless plane. A second block of same mass
m is placed on it and is connected to a spring
constant k, the two blocks are pulled by distance A. Block
Q oscillates without slipping. What is the maximum
value of frictional force between the two blocks.
a) kA/2 b) kA
c)  g) zero
Ans: a)
30. A beam of white light is incident on glass air
interface from glass to air such that green light just
suffers total internal reflection. The colours of the light
which will come out to air are
a) violet, indigo, blue
b) all colours except green
c) yellow, orange, red
d) white light
Ans: c)
Condition for light to transmit is
31. Six charges of equal magnitude, 3 positive and
3 negative are to be placed on PQRSTU corners of a regular hexagon, such that field at the centre is
double that of what it would have been if only one +ve
charge is placed at R
a) +, +, +, _, _, _ b) _, +, +, +, _, _
c) _, +, +, _, +, _ d) +, _, +, _, +, _
Ans: c)
32. A gaussian surface in the figure is shown by
dotted line. The electric field on the surface will be
a) due to  only
b) due to  only
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c) zero
d) due to all
Ans : d)
33. A horizontal circular plate is rotating about a
vertical axis passing through its centre with an
angular velocity  . A man sitting at the centre having
two blocks in his hands stretches out his hands so
that the moment of inertia of the system doubles. If
the kinetic energy of the system is K initially, its
final kinetic energy will be
a) 2K b) K/2
c) K d) K/4
Ans: b)
34. A particle is acted by a force F = kx, where k is a
+ve constant. Its potential energy at x = 0 is zero.
Which curve correctly represents the variation of
potential energy of the block with respect to x
a)  b) 
c)  d) 
Ans : b)
35. An equilateral prism is placed on a horizontal
surface. A ray PQ is incident onto it. For minimum deviation
a) PQ is horizontal
b) QR is horizontal
c) RS is horizontal
d) any one will be horizontal
Ans: b)
For minimum deviation, i = e.
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