Test Your Knowledge - Free MCQ PRACTICE
by Saksham Chaudhry : Paschim Vihar, New Delhi 110063 T: 1142316457, 9810570740
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. lf momentum is increased by 20%, then kinetic energy increases by
A. 55%
B. 77%
C. 66%
D. 44%

2. Moment of inertia of a uniform disc about a diameter is I. Its moment of inertia about an axis perpendicular to its plane and passing through a point on its rim will be
A. 51
B. 31
C. 41
D. 61

3. The decrease in the potential energy of a ball of mass 20 kg which falls from a height of 50 cm is
A. 98 J
B. 968 J
C. 1980 J
D. None of these

4. A neutron makes a head on elastic collision with a stationary deuteron. The fractional energy loss of the neutron in the collision is
A. 16/81
B. 8/9
C. 8/27
D. 2/3

5. Hard X-rays for the study of fractures in bones should have a minimum wavelength of 1E-11 m. The accelerating voltage for electrons in X-ray machine should be
A. Less than 124.2 kV
B. More than 124.2 kV
C. Between 60 kV and 70 kV
D. 100 kV

6. On increasing the reverse bias to a large value in a pn junction diode, the current
A. remains fixed
B. suddenly increased
C. decreases slowly
D. increased slowly

7. A soap film is formed on a wire ring held vertically and allowed to drain. A diffuse source oi while light is observed by reflection in the soap film. In this connection indicate the wrong staternent
A. The colours are due to refraction of light by the wedge~shaped film
B. The thickness of the film is of the same order as the wavelength of visible light
C. The band of colours move downwards as the film drains
D. Just before the film breaks. it may appear black at the top

8. If the universal gas constant is R and Boltzmann constant is K, then number of molecules in a mol of hydrogen will be
A. K/R
B. R/2K
C. R/K
D. 2R/K

9. An earthquake generates both transverse 8 and longitudinal P sound waves in the earth. The speed of 8 waves is about 4.5 km/s and that of P waves is about 8.0 km/s. A seismograph records P and 8 waves from an earthquake. The first P wave arrives 4.0 min before the first 8 wave. The epicenter of the earthquake is located at a distance of about
A. 25 km
B. 8 250 km
C. 2500 km
D. 5000 km

10. In an ideal parallel LC circuit, the capacitor is charged by connecting it to a dc source which is then disconnected. The current in the circuit
A. Becomes zero instantaneously
B. Grows monotonically
C. Decays monotonically
D. Oscillates instantaneously

11. A bomb of mass 3.0 kg explodes in air into two pieces of masses 2.0 kg and 1.0 kg. The smaller mass goes at a speed of 80 m/s. The total energy imparted to the two fragments is
A. 1.07 kJ
B. 2.14 kJ
C. 2.4 kJ
D. 4.8 kJ

12. Which of the following relations between weber, second, ampere and volt is correct ?
A. weber/second = volt
B. weber x second = volt
C. weber/second = ampere
D. weber x second = ampere

13. A boat at anchor is rocked by waves whose crests are 100 m apart and velocity is 25 m/sec. The boat bounces up once in every
A. 2500 s
B. 75 s
C. 4 s
D. 0.25 s

14. A proton and an alpha particle enter uniform magnetic field with the same velocity. The period of rotation of the alpha particle will be
A. the same as that of proton
B. three times that of proton
C. two times that of proton
D. four times that of proton

15. Moving with the same velocity, which of the following has the longest de Broglie wavelength ?
A. neutron
B. proton
C. beta - particle
D. alpha - particle

16. The direction of the force exerted on a surface by a liquid at rest is
A. Normal to the surface
B. Parallel to the surface
C. tangential to the surface
D. 30 to the surface

17. In the experiment for the determination of elm of electron by the Thomson method, elecl and magnetic fields are
A. Parallel and both are perpendicular to the motion of electron
B. Both mutually parallel and also parallel to the motion of the electron
C. Both mutually perpendicular and also perpendicular the motion of electron
D. Both mutually perpendicular and have no relation with motion of the electron

18. A beam of parallel rays is brought to focus by a plano-convex lens. A thin concave lens of the same focal length to joined to the first lens. The effect of this is
A. the focus shifts to infinity
B. the focal point shifts towards the lens by a small distance
C. the focal point shifts away from the lens by small distance
D. the focus remains undisturbed

19. The voltage oi clouds is 4E6 volt with respect to ground. In a lightening strike lasting 100 m sec. charge of 4 conlombs is delivered to the ground. The power oi lightening strike is
A. 160 MW
B. 80 MW
C. 2O MW
D. 500 KW

20. A stone of mass m is tied to a string of length l and rotated in a circle with a constant speed v. If the string is released, the stone flies
A. Tangential outward
B. Radically outward
C. Radially inward
D. With an acceleration mv2/l

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