NEET Physics - New - Electromagnetic Induction and Alternating Currents

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Question - 1

A metallic rod of mass per unit length 0.5 kg/m is lying horizontally on a smooth inclined plane which makes an angle of 30° with the horizontal. The rod is not allowed to slide down by flowing a current through it when a magnetic field of induction 0.25 T is acting on it in the vertical direction. The current flowing in the rod to keep is stationary is :

  • A 7.14 A
  • B 5.98 A
  • C 14.76 A
  • D 11.32

Question - 2

Two cities are 150 km apart. Electric power is sent from one city to another city through copper wires. The fallof potential per km is 8 volt and the average resistance per km is 0.5Ω. The power loss in the wire is:

  • A 19.2 W
  • B 19.2 kW
  • C 19.2 J
  • D 12.2 kW

Question - 3

A thin semicircular conducting ring (PQR) of radius 'r' is falling with its plane vertical in a horizontal magnetic field B, as shown in figure. The potential difference developed across the ring when its speed is v, is :

  • A Zero
  • B Bvπr2/2 and P is at higher potential
  • C πrBv and R is at higher potential
  • D 2rBv and R is at higher potential

Question - 4

In a coil of resistance 10Ω the induced current developed by changing magnetic flux through it, is shown in figure as a function of time. The magnitude of change in flux through the coil in Weber is :

  • A 8
  • B 2
  • C 6
  • D 4

Question - 5

A thin ring of radius R meter has charge q coulomb uniformly spread on it. The ring rotates about its axis with a constant frequency of f revolutions/so The value of magnetic induction in Wb/m2 at the centre of the ring is :

  • A μ0qf/2πR
  • B μ0q/2πfR
  • C μ0q/2fR
  • D μ0qf/2R

Question - 6

A particle of mass m, charge Q and kinetic energy T enters a transverse uniform magnetic field of induction B. After 3 seconds the kinetic energy of the particle will be :

  • A 4 T
  • B 3 T
  • C 2 T
  • D T

Question - 7

A coil of inductance 300 mH and resistance 2 Ω is connected to a source of voltage 2 V. The current reaches half of its steady state value in :

  • A 0.05 s
  • B 0.1 s
  • C 0.15 s
  • D 0.2 s

Question - 8

The self inductance of the motor of an electric fan is 10 H. In order to impart maximum power at 50 Hz, it should be connected to a capacitor of capacitance:

  • A 4 μF
  • B 8 μF
  • C 1 μF
  • D 2 μF

Question - 9

The magnetic flux linked with a coil, in webers, is given by the equations φ=3t2+4t+9. Then the magnitude of induced e.m.f. at t = 2 second will be:

  • A 2 volt
  • B 4 volt
  • C 8 volt
  • D 16 volt

Question - 10

A copper ring is held horizontally and a bar magnet is dropped through the ring with its length along the axis of the ring. The acceleration of the falling magnet while it is passing through the ring is :

  • A Equal to that due to gravity
  • B Less than that due to gravity
  • C More than that due to gravity
  • D Depends on the diameter of the ring and the length of the magnet