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 frog can be levitated in a magnetic field produced by a current in a vertical solenoid placed below the frog. This is possible because the body of the frog behaves as
A. Paramagnetic
B. Diamagnetic
C. Ferromagnetic
D. Antiferromagnetic
2. In short wave communication waves of which of the following frequencies will be reflected back by the ionospheric layer having electron density 1011 per m-3?
A. 2 MHz
B. 10 MHz
C. 12 MHz
D. 18 MHz
3. The direction of the angular velocity vector is along
A. The tangent to the circular path
B. The inward radius
C. The outward radius
D. The axis of rotation
4. Two blocks of equal mass 3 kg, connected by a light string, are placed on a horizontal surface which is not frictionless. If a force of 20 N is applied in the horizontal direction on a block, the acceleration of each block is 0.5 m/s/s. Assuming that the frictional forces on the two blocks are equal, the tension in the string will be
A. 60 N
B. 40 N
C. 20 N
D. 0 N
5. 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
6. A proton is about 1840 times heavier than an electron . When it is accelerated by potential difference of 1 kV, its kinetic energy will be
A. 1840 ke V
B. 1./1840 ke V
C. 1 ke V
D. 920 ke V
7. To a germanium sample, traces of gallium are added as an impurity. The resultant sample would behave like
A. A conductor
B. A p-type semiconductor
C. An n-type semiconductor
D. An insulator
8. A stone tied with a string, is rotated in a vertical circle. The minimum speed with which the string has to be rotated ?
A. is independent of the mass of the stone
B. is independent of the length of the string
C. decreases with increasing mass of the stone
D. decreases with increasing in length of the string
9. To use a transistor as an amplifier
A. Emitter-base junction is forward biased and collector-base junction is reversed biase
B. both junctions are reverse biased
C. both junctions are forward biased
D. It does not matter how the transistor is biased, it always works as an amplifier
10. When an electron positron pair annihilates, the energy released is about
A. 0.8E-13 J
B. 1.6E-13
C. 3.2E-13 J
D. 4.8E-13 J
11. Which of the following is not a vector quantity?
A. speed
B. velocity
C. torque
D. displacement
12. A diatomic gas initially at 18°C is compressed adiabtically to 1/8 of its original volume. The temperature after compression will be
A. 144°C
B. 891°C
C. 887°C
D. 18°C
13. A proton of energy 4 eV is incident on a metal surface whose work function is 2 eV. The minimum reverse potential to be applied for stopping the emission of electrons is
A. 2V
B. 24V
C. 6V
D. 8V
14. The amount of heat, measured in calories, needed to raise the temperature of 1 gram of substance by 1 degree centigrade ls known as
A. Heat of fusion
B. Specific heat
C. Coefficient of expansion
D. Latent heat
15. A soap bubble is vacuum has a radius of 3 cm and another soap bubble in vacuum has a radius of 4cm. If the two bubbles coalesce under isothermal conditionals the radius of the new bubble will be
A. 7 cm
B. 5 cm
C. 4.5 cm
D. 2.3 cm
16. 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
17. 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
18. In simplest terms, the energy of a wave is directly proportional to the square of its
A. height
B. refraction
C. reflection
D. length
19. 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
20. A nucleus of mass number A, originally at rest, emits an alpha - particles with speed v. The daughter nucleus recoils with a speed
A. 2v/A + 4
B. 4v/A + 4
C. 4v/A - 4
D. 2v/A - 4
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