question_answer

Direction: Q.31 to Q.35

As shown in figure a solenoid where the wire is coiled around a cylinder, each wire loop in this coil acts as if it was a separate circular wire carrying the same current l, the current in the coiled wire and the dense enough array of such loops may be approximated by a cylindrical current sheet with the current density.

\[J=I\times (N/L)=I\times L\,\,(loops/solenoid\,\,length)\]

For simplicity, let's assume a long solenoid (length >> diameter) which we approximate as infinitely long. For a long solenoid (compared to its diameter), the magnetic field inside the solenoid is approximately uniform and approximately parallel to the axis, except near the ends of the solenoid. Outside the solenoid, the magnetic field looks like the field of a physical dipole, with the north pole at one end of the solenoid and the south pole at the other end and is approximately negligible.

Read the given passage carefully and give the answer of the following questions.

Which of the following material can be used to make loops around the cylinder?

A) Plastic                          

B)             Glass   

C)             Quartz                          

D)             Copper