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Answers for Questions in Physics(AIEEE 2007)
1. A block of
mass `m is connected to another block of mass `M by a spring (massless) of spring constant `k
. Ans.
2. Two lenses
of power -
15D and +5D are in contact
.. Ans.-
10 cm 3. One end of a
thermally insulated rod is kept at a temperature T1 and the other at
T2. The rod is
Ans.(k1l2T1 + k2l1T2)
/ (k1 l2 + k2 l1) 4. A sound
absorber attenuates the sound level by 20 dB. The
Ans.
100 5. If CP
and CV denote the specific heats of nitrogen per unit mass
. Ans.CP
-
CV = R/28 6. A charged
particle moves through a magnetic field
. Ans.the
momentum changes but the kinetic energy is constant. 7. Two
identical conducting wires AOB and COD are placed at right angles to each
other. The wire AOB carries
Ans.
8. The
resistance of a wire is 5 ohm at 50°
C and 6 ohm at 100°
C. The
. Ans.4
ohm 9. A parallel
plate condenser with a dielectric of dielectric constant K between the plates
has a capacity C
Ans.zero
10. If gE and gm are the accelerations due
to gravity on the surfaces of the earth and the moon respectively and if Millikans oil
.. Ans.1 11. A circular disc
of radius R is removed from a bigger circular disc of radius 2R
Ans.
12. A round uniform
body of radius R, mass M an dmoment of inertia `I
,
Ans.
13. Angular momentum of the particle
.. Ans.
Zero torque 14. A 2 kg block
slides on a horizontal floor with a speed of 4 m/s. It strikes a uncompressed
spring, Ans.5.5
cm 15. A particle is
projected at 60°
to the horizontal
.. Ans.
K/4 16. In a Youngs
double slit experiment the intensity at a point where the path difference is
Ans.
17. Two springs, of
force constants k1 and k2, are connected to a mass m as
shown. The frequency of
.. Ans.2f 18. When a system
is taken from state i to state f along the path iaf, it is found
. Ans.6 cal 19. A particle of
mass m executes simple harmonic motion with amplitude `a and frequency `v
.. Ans.p
2ma2v2 20. The displacement of an object
attached to a spring and executing simple
. Ans.0.5
s 21. In an a.c.
circuit the voltage applied is E = E0 sin w
t. The
resulting current in the circuit
.. Ans.P
=
zero 22. An electric
charge 10-
3m
C is placed at the origin (0, 0) of X
-
Y co-ordinate system. Two points A and B
.. Ans.zero
23. A battery is
used to charge a parallel plate capacitor till the potential difference between
the plates becomes
.. Ans.
24. An ideal coil
of 10 H is connected in series with a resistance of 5 W
and a
battery of 5 V. 2 seconds
Ans.(1 -
e-
1) 25. A long straight
wire of radius `a carries a steady current i. the
current
. Ans.1 26. A current I
flows
along the length of an infinitely long, straight, thin
.. Ans.the
magnetic field at any point inside the pipe is zero. 27. If M0
is the mass of an oxygen isotope 8O17, MP and
MN
.. Ans.(MO
-
8MP -
9MN)C2 28. In gamma ray
emission
. Ans.there
is no change in the proton number and the neutron number. 29. If in a p-n junction diode, a square
input signal
. Ans.
30. Photon of
frequency u
has a momentum associated
Ans.h
u
/c 31. The velocity of
a particle is v = v0 + gt + ft2.
If its position is
. Ans.v0
+ g/2 + f/3 32. For the given
uniform square lamina ABCD, whose centre
. Ans.I
AC = I
EF 33. A point mass oscillates along the
x-axis according to the law x = x0 cos (w
t -
p
/4)
Ans.A
=
x0w
2, d
= 3p
/4 34. Charges are placed on the vertices of
a square as shown. Let
Ans.
35. The half-life period of a radio-active
element X is same as the mean life
.. Ans.Y
will decay faster than X 36. A Carnot
engine, having an efficiency of Ans.90
J 37. Carbon, silicon
and germanium have four valence electrons each. At room temperature
Ans.The
number of free electrons for conduction is significant only
in Si and Ge but small in
C. 38. A charged particle with charge q
enters a region of constant, uniform and mutually orthogonal fields
. Ans.
39. The potential at a point x (measured
in m
m) due to some charges situated on the x-axis is given by
Ans.10/9
Volt/m
m and in the +ve x direction 40. Which of the following transitions in
hydrogen atoms
. Ans.n
= 2 to n = 1
 |
(The Centre of Mass of the new Disc will have to be taken as
.
be the electric field and V the potential
..