Question

Two small bar magnets each of magnetic dipole moment M are arranged at separation 2d as shown in figure with their axes parallel to each other. The magnetic field intensity at point P will be

• A. Zero
• B. $\frac{{\mu }_0}{4\pi }\frac{2M}{d^3}$
• C. $\frac{{\mu }_0}{4\pi }\frac{4M}{d^3}$
• D. $\frac{{\mu }_0}{4\pi }\frac{2\sqrt{2M}}{d^3}$

Answer 1

The correct option is C $\frac{{\mu }_0}{4\pi }\frac{4M}{d^3}$

Given:

two bar magnets are in parallel position

Solution:

for the lower magnet the magnetic field will be in leftward direction
and same for the upper magnet.
Hence the intensity will be added and doubled.
now for a bar magnet field intensity in axial position is=$\frac{\mu \cdot }{4\pi }\times \frac{2M}{d^3}$.
so net field intensity will be $\frac{\mu \cdot }{4\pi }\times \frac{4M}{d^3}$.
Correct opt is:C