Discussion Forum



1)

A steady current I flows along an infinitely long hollow cylindrical conductor of radius R. This cylinder is placed coaxially inside an infinite solenoid of radius 2R. The solenoid has n turns per unit length and carries a steady current I. Consider a point p  at a distance r from the common axis . The  correct statement (s)  is (are)


A) In the region 0 < r < R, the magnetic field is non-zero

B) In the region R < r < 2R the magnetic field is along the common axis

C) In the region R < r < 2R , the magnetic field is tangential to the circle of radius r, centered on the axis

D) In the region r >2 R, the magnetic field is non -zero

Answer:

Option A,D

Explanation:

1052021283_p3.JPG

in the region , 0<r<R

 Bp=0,

 $B_{Q}\neq 0$ , along the axis

 $\therefore$   $B_{net}\neq 0$ 

 in the region R<r<2R

 $B_{p}\neq 0$  tangential to the circle  of radius r, centred on the axis

 $B_{Q}\neq 0$  , along the axis

 $\therefore $  $B_{net}\neq 0$ neither in the directions mentioned in options (b) and (c) 

 In the region  , r>2R

$B_{p}\neq 0$

$B_{Q}\neq 0$

$\therefore$   $B_{net}\neq 0$