1 Electrostatics
In the electric field experiment, along an electric field line the double pronged DVM probe:
(1) Always points directly to one of the electrodes.
(2) Will read zero.
(3) Will read a minimum.
(4) Will read a maximum.
2 Magnetic Effects of Current and Magnetism
A conventional electric current flows due east in a high voltage power line. What would be the direction of the resulting magnetic field directly below the power line?
1) north 2) east 3) south 4) west
3 Kinetic Theory of gases
7 moles of a tetra-atomic non-linear gas A at 10 atm and T K are mixed with 6 moles of another gas B at T/3K and 5atm in a closed, rigid vessel without energy transfer with surroundings. If final temperature of mixture was 5T/6K, then atomcity of gas B is (Assuming all modes of energy are active)
1) 1 2) 4 3) 2 4) 3
$$C_{v}$$ of gas $$A= \displaystyle \frac{3}{2}R+ \displaystyle \frac{3}{2}R+6R=9R$$ Let $$C_{v}$$ of gas $$B=X$$ Heat lost by gas $$A=7 \times 9R \times (T- \displaystyle \frac{5T}{6})$$ Heat gained by gas $$B=6X( \displaystyle \frac{5T}{6}- \displaystyle \frac{T}{3})$$ $$\Rightarrow 63R( \displaystyle \frac{T}{6})=6X( \displaystyle \frac{T}{2})=X= \displaystyle \frac{7}{2}R$$ $$\therefore$$ gas is diatomic. and atomcity of gas is 2.
4 Magnetic Effects of Current and Magnetism
A conductor of length 2 m carrying current 2 A is held parallel to an infinitely long conductor carrying current of 12 A at a distance of 100 mm, the force j on a small conductor is: 1) 8.6 x 10−5N 2) 6.6 x 10−5N 3) 9.6 x 10−5N 4) 7.6 x 10−5N
5 Dual Nature of Matter and Radiation
Assuming an average energy of 200 MeV per fission, calculate the number of fissions per second needed for a 500 megawatt reactor. (1MeV is 1.60 x 10-13 Joules ) Assume (unrealistically) an efficiency of 100%.
1) 1.50 x 1024
2) 1.56 x 1019
3) 1.45 x 1022
4) 2.50 x 106
6 Gravitation
The ratio of the time periods for two satellites of equal mass in circular orbits of radii R and 16 R is 1) 1 : 64 2) 1 : 16 3) 16 : 1 4) 64 : 1
7 Oscillations
A pendulum having a period of oscillation of 2 seconds is taken on a planet where g is four times that on the earth. The period of the pendulum would be
1) 4 s
2) 2 s
3) 1 s
4) ½ s
SOLUTION
8 Electrostatics
The electirc field strength at a distance rr from the centre of a charged sphere of radius r is E. If r > R, how much work will be done in bringing a test charge q0 from infinity to that point, is
(1) q0RE (2) 1/2 q0RE (3) q0 r E (4) 1/2 q0 r E
Solution
E=V /r
or E =V / r , V = rE , U=q0V
=q0rE
9 Wave Optics
The 6563 ?A Hα line emitted by hydrogen in a star is found to be red-shifted by 15 A?. Estimate the speed with which the star is receding from the Earth.
1) 68.6×105ms−1 2) 2.86×105ms−1 3) 6.86×105ms−1 4) 1.86×105ms−1
$$\lambda^{'}-\lambda=\dfrac{v}{c}\lambda\Rightarrow v=\dfrac{c}{\lambda}(\lambda{'}-\lambda)$$
10 Kinematics
A vehicle travels a distance of 160 km in 5 hours. The average speed is (1) 32 km/hr (2) 40 km/hr (3) 80 km/hr (4) 165 km/hr
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