Question

Magnetic induction at a point on the axial line of a short bar magnet is $B$ towards East. If the magnet is turned through ${90}^o$ in clock wise direction, then magnetic induction at the same point is (Neglect Earth's magnetic field).

• A. $B/4$ towards East
• B. $B/2$ towards West
• C. $B/2$ towards North
• D. $B/2$ towards South

Answer 1

Answer: (C)

$B/2$ towards North

$B_q=\frac{2{\mu }_{0}m}{4\pi d^3}=B$
$B_l=\frac{{\mu }_{0}m}{4\pi d^3}$
$B_a=2Be$
$B_e=\frac{B_q}{2}$
$=\frac{B}{2}$