Q. Two identical magnetic dipoles of magnetic moment 2 $Am^{2}$ are placed at a separation of 2 m with their axis perpendicular to each other in air. The resultant magnetic field at a mid-point between the dipoles is
A) $4\sqrt{5}\ \times 10^{- 5}\ T$
B) $2\sqrt{5}\ \times 10^{- 5}\ T$
C) $4\sqrt{5}\ \times 10^{- 7}\ T$
D) $2\sqrt{5}\ \times 10^{- 7}\ T$
Explanation
(d) $R = \sqrt{P^{2} + Q^{2}}$
$B = \left\lbrack \left\{ \frac{2P}{(d/2)^{3}\ } \right\}^{2} + \left\{ \frac{P}{(d/2)^{3}} \right\} \right\rbrack^{1/2} \times 10^{- 7}$
$\ \ \ \ = \sqrt{\left( 4^{2} + 4 \right)} \times 10^{- 7}$
$\ \ \ \ = \sqrt{20} \times 10^{- 7} = 2\sqrt{5}\ \times 10^{- 7}$ T
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.