Question

The adjacent figure shows the cross- section of a long rod with its constant perpendicular to the plane of the paper. It carries a constant current flowing along its length $B_1,B_2,B_3$ and $B_4$ respectively represent the length magnetic fields due to the current in the rod at point 1, 2, 3, and 4 lying at different separations from the centre O, as shown in the figure. Which of the following shall hold true.

• A. $B_1>B_2\ne 0$
• B. $B_2>B_3\ne 0$
• C. $B_1=B_2=B_3=0$
• D. $B_3>B_4\ne 0$

Answer 1

The correct option is A $B_1>B_2\ne 0$

The Magnetic Field lines through an area represents the flux (flux is the field lines passing through an area Thus, the degree of closeness of magnetic field lines represents the relative strength of the magnet