A fresh set of 20 random questions is generated every time you open this page and every time you refresh it.For each of the following multiple choice questions, choose the most appropriate answer :
1. A spring of of force constant it is cut into three equal pieces. If these three pieces are connected in parallel, the force constant of the combination will be
A. 3k
B. 9k
C. k
D. k/3
2. Two metallic charged spheres whose radii are 20 cm and 10 cm respectively, have each 150 micro-coulomb positive charge. The common potential after they are connected by a conducting wire is
A. 13.5E6 volts
B. 1.8E6 volts
C. 4.5E7 volts
D. 9E6 volts
3. The amount of a liquid’s cohesive force per unit of length is called
A. depression
B. adhesion
C. apparent weight
D. surface tension
4. Consider an n-p-n transistor amplifier in common emitter configuration. The current gain of the transistor is 100. If the collector current changes by 1 mA, what will be the change in emitter current ?
A. 11.1mA
B. 1.01mA
C. 10 mA
D. 0.01 mA
5. A esound absorber attenuates the sound leveI by 20 dB.The intensity decreases by a factor of
A. 1000
B. 10000
C. 10
D. 100
6. By sucking through a straw. a student can reduce the pressure in his lungs to 750 mm of Hg density 13.6 gm/cc. Using the straw. he can drink water from a glass upto a maximum depth of
A. 10 cm
B. 75 cm
C. 13.6 cm
D. 1.36 cm
7. If an electron and a photon propagate in the form of waves having the same wavelength, it implies that they have the same
A. Energy
B. Momentum
C. Velocity
D. Angular momentum
8. An electron is travelling along the x-directlon . It encounters a magnetic field in the y-direction . Its subsequent motion will be
A. Straight line along the x-direction
B. A circle in the xz-plane
C. A circle in the yz-plane
D. A circle in the xy-plane
9. The ground state energy of hydrogen atom is - 13.6 eV. What is the potential energy of the electron in this state ?
A. 0 eV
B. -27.2 eV
C. 2 eV
D. 1 eV
10. The particle accelerated at a constant rate from 23 mi/hr. to 58 mi./hr. in 3.5 sec. Its acceleration was
A. 10 mi./hr. per sec
B. 58 mi/hr per sec
C. 23 mi./hr. per sec
D. less than 10 mi./hr. per sec
11. The earth revolves about the sun in an elliptical orbit with mean radius 9.3E7 m in a period of 1 year. Assuming that there are no outside influences
A. The earth's kinetic energy remains constant
B. The earth’s potential energy remains constant
C. The earth's angular momentum remains constant
D. All three above are correct
12. An electric fan has blades of length 30 cm measured from the axis of rotation. If the fan is rotating at 120 rpm, the acceleration of a point on the tip of the blade is ?
A. 1600 m/s/s
B. 47.4 m/s/s
C. 23.7 m/s/s
D. 50.55 m/s/s
13. A telescope has an objective lens of focal length 200 cm and an eye piece with focal length 2 cm. If this telescope is used to see a 50 metre tall building at a distance of 2 km. what is the height of the image of the building formed by the objective lens ?
A. 2cm
B. 5cm
C. 10cm
D. 1 cm
14. The condition that the image is not formed on the screen placed on the other side of lens, when the object is placed before the lens
A. Between 2F and F
B. Between F and optical centre
C. Between 2F and infinity
D. At F
15. If a planet of given density were: made larger keeping its density unchanged its force of attraction for an object on its surface would increase because of increased mass of the planet but would decrease because of larger separation between the centre of the planet and its surface. Which effect would dominate?
A. Increase in mass
B. Increase in radius
C. Both affect the attraction equally
D. None of the above
16. A parallel plate capacitor is made by stacking n equally spaced plates connected alternatively. If the capacitance between any two adjacent plates is C then the resultant capacitance is
A. n-1C
B. n+1C
C. C
D. nC
17. If an object is moving with a constant acceleration, the net force acting on that body ts
A. increasing
B. decreasing
C. constant
D. zero
18. A bullet is fired from a gun with a speed of 1000 m/s in order to hit a target 100 m away. At what height above the target should the gun be aimed? The resistance of air is negligible and g=10 m/s2
A. 5 cm
B. 10 cm
C. 15 cm
D. 20 cm
19. A 500 kg car takes a round turn of radius 50 m with a velocity of 36 km/h. The centripetal force is ?
A. 250N
B. 750N
C. 1000N
D. 1250N
20. A leaf which eontains only green pigments, is illuminated by a laser light of wavelength 0.6828 micron. It would appear to be
A. Brown
B. Black
C. Red
D. Green
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