Moving Charges and Magnetism-Quiz-13

MOVING CHARGES AND MAGNETISM-13

Dear Readers,

JEE Advanced Physics Syllabus can be referred by the IIT aspirants to get a detailed list of all topics that are important in cracking the entrance examination. JEE Advanced syllabus for Physics has been designed in such a way that it offers very practical and application-based learning to further make it easier for students to understand every concept or topic by correlating it with day-to-day experiences. In comparison to the other two subjects, the syllabus of JEE Advanced for physics is developed in such a way so as to test the deep understanding and application of concepts.

Q1. Figure shows three cases: in all cases the circular part has radius r and straight ones are infinitely long. For the same current the ratio of field B at centre P in the three cases B_1:B_2:B_3 is

•    (-π/2):(π/2):(3π/4-1/2)
•   (-π/2+1):(π/2+1):(3π/4+1/2)
•   (-π/2):(π/2):(3π/4)
•   (-π/2-1):(π/2-1/4):(3π/4+1/2)

Solution

Q2.A steady current is flowing in a circular coil of radius R, made up of a thin conductive wire. The magnetic field at the centre of the loop is B_L. Now, a circular loop of radius R/n is made from the same wire without changing its length, by unfloding and refolding the loop, and the same current is passed through it. If new magnetic field at the coil is B_C, then the ratio B_l/B_C is

•   1:n^2
  
  
  
  
•   n^(1/2)
  
  
  
  
•   n:1
  
  
  
  
•   none of these
  
  
  
  

Solution

Q3. Four infinite thin current sheets are placed in YZ plane. The 2D view of the arrangement is as shown in figure. Direction of current has also been shown in the figure. The linear current density, i.e., current per unit width in the four sheets are I,2I,3I and 4I, respectively

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•   
  
  
  
•   
  
  
  
•   
  
  
  

Solution

Q4. A circular loop is kept in that vertical plane which contains the north-south direction. It carries a current that is toward north at the topmost point. Let A be a point on the axis of the circle to the east of it and B a point on this axis to the west of it. The magnetic field due to the loop

•   Is towards east at A and toward west at B
•   Is towards west at A and toward east at B
•   Is towards east at both A and B
•   Is towards west at both A and B

Solution

Q5.  A magnetic needle is kept in a non-uniform magnetic field. It experiences

•  A force and a torque
•  A force but not a torque
•  A torque but not a force
•  Neither a force nor a torque

Solution
 

Q6. A loop carrying current I lies in the x-y plane as shown in the figure. The unit vector k ̂ is coming out of the plane of the paper. The magnetic moment of the current loop is

•  a^2 Ik ̂
•   (π/2+1) a^2 Ik ̂
• -(π/2+1) a^2 Ik ̂
•  (2π+1) a^2 Uk ̂

Solution

Q7.A charged particle beings to move from the origin in a region which has a uniform magnitude field in the x-direction and a uniform electric field in the y-direction. Its speed is v when it reaches the point(x,y,z). Then, v will depend

•   Only on x
•   Only on y
•  On both x and y, but not z
•   On x,y and z

Solution

Q8.An electron is launched with velocity v vector in a uniform magnetic field B vector. The angle θ between v and B lies between 0 and π/2. Its velocity vector v vector returns to its initial value in a time interval of

•   2πm/eBAlong positive y-axis
•   (2×2πm)/eB
•  πm/eB
•  Depends upon angle between v vector and B vector

Solution

Q9.Two metal strips of length leach are placed parallel to each other in contact with an electric circuit as shown in Fig. The entire in which uniform magnetic field is existing in vertical direction The distance travelled by the wire as a function of time is best given by 1/2×EBb/Rm×t^2 for t<t_0 and l+EBb/Rm(t-t_0) for t≥t_0

•   l+EBb/Rm(t-t_0) for t≥t_0
•  1/2×EBb/Rm×t^2 for all t
•  1/2×EBb/Rm×t^2 for t≤t_0 and then the wire stops
•  1/2×EBb/Rm×t^2 for t≤t_0 and l+E3b/Rm×t for t>t_0 Where t_0=√((2 lmR)/EBb)

Solution

Q10. A current I flows along the length of an infinitely long, straight, thin walled pipe. Then

•   ̂The magnetic field at all points inside the pipe is same, but not zero
•  The magnetic field at any point inside the pipe is zero
•  The magnetic field is zero only on the axis of the pipe
• The magnetic field is different at different points inside the pipe

Solution