Question

. The value of electric field at the centre of hollow spherical metallic shell of radius 5 m, having positive charge of 10 C is *

(a) 2 NC⁻¹

(b) 0

(c) 10 NC⁻¹

(d) 5 NC⁻¹

Q3. The capacitance of a parallel plate capacitor depends upon *

(a) area of plates

(b) distance between the plates

(c) dielectric constant of medium between the plates

(d) all of the above

Q4. The specific resistance of a wire *

(a) Varies with its length

(b) Varies with its area of cross-section

(c) Varies with its mass

(d) does not depend upon its mass, length and area of cross-section

Q5.When two unequal resistors are connected in parallel in a circuit *

(a) the current is same in both the resistors

(b) a larger current flows through the larger resistor

(c) the voltage drops across both the resistors is same

(d) all of the above

Q6. A material ,which magnetizes to a small extent in the same direction to the applied external magnetic field is *

(a) ferrimagnetic material

(b) anti-ferromagnetic material

(c) diamagnetic material

(d) paramagnetic material

Q7.Two parallel wires are carrying electric current of equal magnitude in the same direction. They exert *

(a) An attractive force on each other

(b) No force on each other

(c) A repulsive force on each other

(d) A rotational torque on each other

Q8. Horizontal component of earth’s magnetic field at a place is √3 times the vertical component. The value of dip at this place is *

(a) 30°

(b) 45°

(c) 60°

(d) 90°

Q9.The SI unit of magnetic dipole moment is *

(a) ampere metre

(b) ampere

(c) ampere metre²

(d) tesla

Q10. To convert a galvanometer into a voltmeter *

(a) a low resistance is connected in parallel

(b) a high resistance is connected in parallel

(c)a low resistance is connected in series

(d)a high resistance is connected in series

Q11. For a short bar magnet, magnetic field intensity at a point lying at the same distance from the center of magnetic dipole on the axial line of the magnet ( Baxial)is *

(a) equal to magnetic field intensity on the equatorial line (Bequatorial)

(b) twice the magnetic field intensity on the equatorial line (Bequatorial)

(c) zero

(d) four times magnetic field intensity on the equatorial line (Bequatorial)

Q12. The alloys Alnico and steel are used for making *

(a) transformer

(b) electromagnet

(c) permanent magnet

(d) all of the above

Q13. In a transformer no of turns in the primary coil is 140 and that in the secondary coil is 280. If current in primary is 4A, the current in secondary is *

(a) 4 A

(b) 6 A

(c) 2 A

(d) 10 A

Q14. At resonance, in LCR series circuit *

(a) Operating frequency ω = natural frequency ωo

(b) Impedance Z is minimum and equals to R

(c) Current in the circuit is maximum

(d) All of the above

Q15. The power factor of an ac circuit is 0.5. Phase difference between voltage and current in this circuit is *

(a) 30°

(b) 45°

(c) 60°

(d) 90

Q16. A15µF capacitor is connected to a 220V, 50Hz a.c. supply. Its capacitive reactance is *

(a) 200 .5 Ω

(b) 210.2 Ω

(c) 212.3 Ω

(d) 215.4 Ω

Q17.When a.c. passes through pure inductor then *

(a) e.m.f. leads the current by π/2

(b) e.m.f. lags the current by π/2

(c) e.m.f. leads the current by π/4

(d) e.m.f.and current are in the same phase

Q18.Which of the following waves is not electromagnetic in nature? *

(a) Microwaves

(b) X-rays

(c) radio waves

(d) audio waves

Q19. When current in a coil changes from 6 A to 2 A in 0.1 s, and value of induced e.m.f is 40 V . The self-inductance of the coil is *

(a) 1 H

(b) 6 H

(c) 3 H

(d) 0.67 H

Q20.Infrared rays are used in *

(a) in physio therapy

(b) in green house effect

(c) in remote switches

(d) all of the above

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Answer 1

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Answer 2

Explanation:

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