In the following diagram, which particle has highest e/m value?&n

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 Multiple Choice QuestionsMultiple Choice Questions

251.

Assertion:  When a radius of circular loop carrying current is doubled, its magnetic moment becomes four times.

Reason: Magnetic moment depends on area of the loop.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false


252.

What is the magnetic field at a distance R from a coil of radius r carrying current ?

  • μ0 I R22  R2  +  r2 32

  • μ0I R22  R2 + r2 32

  • μ0 I2r

  • μ0 I2R


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253.

In the following diagram, which particle has highest e/m value?

  

  • A

  • B

  • C

  • D


D.

D

When electron enters a region in which there is uniform magnetic field perpendicular to the velocity v, of the electric field, the electron experiences a force F with a magnitude given by following eqaution

    F = e v B

The force is perpendicular to both v and B and its direction can be found by using the right-hand rule. The force will cause the electron to circular orbit with radius r ( uniform circular motion ).

We can equate the forces on the electron

   f = ev × B = evB = m v2r

⇒    e v B = mv2r

 em  1r, if B and v are the same. The radius of curvature of D is minimum. Therefore  em  is maximum.


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254.

Circular  loop  of  a  wire  and a  long  straight  wire  carry currents  Ic  and  Ie respectively  as shown in figure. Assuming  that  these  are  places  in  the same plane, the magnetic  field  will be  zero  at  the  centre of  the loop when separation  H is

  • Ie RIc π

  • Ic RIe π

  • π IcIe R

  • Ie πIc R


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255.

A metallic ring is dropped down, keeping its plane perpendicular to a constant and horizontal magnetic field. The ring enters the region of magnetic field at I = 0 and completely emerges out at  t = T sec. The current in the ring varies as


256.

A conducting ring of radius 1 meter is placed in a uniform magnetic field B of 0.01 tesla oscillating with frequency 100 Hz with its plane at right angle to B. What will be the induced electric field?

  • π volts/m

  • 2 volts/m

  • 10 volts/m

  • 62 volts/m


257.

A proton and an  α -particle, moving with the same velocity, enter into a uniform magnetic field, acting normal to the plane of their motion. The ratio of the radii of the circular paths described by the proton α-particle is

  • 1 : 2

  • 1 : 4

  • 1 : 16

  • 4 : 1


258.

The electric field due to a uniformly charged sphere of radius R as a function of the distance from its centre is represented graphically by


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259.

A circular coil of radius is R carries an electric current. The magnetic field due to the coil at a point on the axis of the coil located at a point on the axis of the coil located at a distance r from the centre of the coil, such that r >> R, varies as 

  • 1r

  • 1r32

  • 1r 2

  • 1r3


260.

The magnetic field due to straight conductor of uniform cross-section of radius  ' a '  and carrying a steady current is represented by


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