Magnetic Effect Of Current MSQ - Physics MCQ

The point charge moves in circle as shown in figure. The magnetic field vectors at a point  P  on axis of circle are   at the instants the point charge is at A and C respectively as shown in the figure.

Hence as the particles rotates in circle, only magnitude of magnetic field remains constant at the point on axis P but its direction changes.

The correct answers are: it is constant in direction only, it is constant in direction and magnitude both, it is not constant in magnitude and direction both.

Disc behaves like made up of coils arranged in a plane in which current is flowing in anti-clockwise direction.
Hence, the field at  A  is direction into the page.
The correct answers are: out of the page, up the page, down the page

As the magnetic field is along the x-axis, the magnetic force will be along negative z-axis from t = 0 to t = T₀ and along positive z-axis from

t = T₀  to  t = 2T₀
For    t = 0  to  t = T₀

At 

y-coordinate = 0 (from figure)
and  z-coordinate = –2R₀  (from figure)

The correct answers are: At  co-ordinates of charge are co-ordinates of charge are  Two extremes from x-axis are at a distance 2R₀  from each other.

Magnetic field at  ‘P’  due to wires (1) and (2) is :

 (out of the paper)

The correct answers are: Magnetic field intensity at P  is zero for all values of  x., If the current in the third wire is  (left to right) then magnetic field will be zero at P  for all values of x., If the current in the third wire is  (right to left) then magnetic field will be zero at  P  for all value of  x.

For cylinder

We can consider the given cylinder as a combination of two cylinders. One of radius ‘R’  carrying current. I  in one direction and other of radius R/2 carrying current I/3 in both directions.

The correct answers are:

Consider a ring of radius x and thickness dx.

Equivalent current in this ring 

dB (due to this ring) 

The correct answers are: directed outward, having magnitude 

Alterante solution
B (inside the conductor) ∝ r,  B(outside the conductor) 

The correct answers are: The magnetic field strength is maximum on the surface, The energy density of the magnetic field outside the conductor varies as inversely proportional to 1/r², where ‘r’  is the distance from the axis.

The correct answers are: Velocity of particle when it comes out from magnetic field is  Time for which the particle was in magnetic field is Distance traveled in magnetic field is 

Electromagnetic force will provide the necessary centripetal force.

⇒ 
 

i.e. the electron will move out after traveling on a semicircular path of radius r = 2d.

The correct answers are: angle subtended by charged particle at the centre of circular path is  2π, the time for which particle will be in the magnetic field is the charged particle will subtended an angle of 90° at the centre of circular path

The particle will move along an arc which is part of a circle of radius

From the figure we can see  r = R

The correct answers are: