In a region, steady and uniform electric and magnetic from Class Physics Moving Charges And Magnetism

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NEET Physics : Moving Charges And Magnetism

Multiple Choice Questions

161.

An electron of mass m and charge q is travelling with a speed v along a circular path of radius r at right angles to a uniform of magnetic field B. If speed of the electron is doubled and the magnetic field is halved, then resulting path would have a radius of

  • r4

  • r2

  • 2r

  • 4r



162.

A particle of charge -16 x 10-18 moving with velocity 10 ms-1 along the x-axis enters a region where a magnetic field of induction B is along the y-axis, and an electric field of magnitude 104 Vm-1 is along the negative z-axis. If the charged particle continues moving along the x-axis, then magnitude of B is

  • 10-3 Wbm-2

  • 103 Wbm-2

  • 105 Wbm-2

  • 1016 Wbm-2



163.

The ratio of voltage sensitivity (VS ) and current sensitivity (IS ) of a moving coil galvanometer is

  • 1G

  • 1G2

  • G

  • G2



164.

A galvanometer acting as a voltmeter should have

  • low resistance in series with its coil

  • low resistance in parallel with its coil

  • high resistance in series with its coil

  • high resistance in parallel with its coil



165.

In a region, steady and uniform electric and magnetic fields are present. These two fields are parallel to each other. A charged particle is released from rest in this region. The path of the particle will be a

  • helix

  • straight line

  • ellipse

  • circle



166.

The coil in a tangent galvanometer is 16 cm in radius. If a current of 20 mA is to produce a deflection of 45°, then the number of turns wound on it, is (Take horizontal component of earth's magnetic field = 0.36 x 10-4 T  and µ0 = 4π x 10-7 WbA-1 m-1 )

  • 229

  • 458

  • 689

  • 916



167.

An α-particle with a specific charge of 2.5 × 107 C-kg-1 moves with a speed of 2 × 105 ms-1 in a perpendicular magnetic field of 0.05 T. Then the radius of the circular path described by it is

  • 8 cm

  • 4 cm

  • 16 cm

  • 2 cm



168.

A straight conductor of length I carrying a current I, is bent in the form of a semicircle. The magnetic field (in tesla) at the centre of the semicircle is

  • π2Il × 10-7

  • πIl × 10-7

  • πIl2 × 10-7

  • πI2l × 10-7



169.

Which of the following relation represents Biot-Savart's law ?

  • dB  = μ04π dl × rr

  • dB  = μ04π dl × rr3

  • dB  = μ04π dl × rr3

  • dB  = μ04π dl × rr4



Short Answer Type

170.

A 50 cm long conductor AB moves with a speed 4 m/s in a magnetic field B = 0.01 Wb/m2 as shown. Find the emf generated and power delivered if resistance of the circuit is 0.1 Ω.



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