Question:

A short bar magnet has a magnetic moment of $0.48\, J\, T^{-1}$. The magnitude and direction of magnetic field produced by the magnet at a distance of $10 \,cm$ from the centre of the magnet on its axis is

Updated On: Sep 26, 2023
  • $0.48 \times 10^{-4}\, T$ along $N-S$ direction
  • $0.28 \times 10^{-4}\, T$ along $S-N$ direction
  • $0.28 \times 10^{-4}\, T$ along $N-S$ direction
  • $0.96 \times 10^{-4}\, T$ along $S-N$ direction
Hide Solution
collegedunia
Verified By Collegedunia

The Correct Option is D

Solution and Explanation

On the axis of the magnet $B = \frac{\mu_{0}}{4\pi} \cdot \frac{2m}{d^{3}}$ Here, $\frac{\mu _{0}}{4\pi } = 10^{-7} \, A\,m^{-2}$ $m = 0.48 \,J \,T^{-1}, d = 10 \,cm = 0.1 \,m$ Then, $B = \frac{10^{-7}\times 2 \times 0.48 }{\left(0.1\right)^{3}}$ $= 0.96 \times 10^{-4}\,T$, along $S-N$ direction.
Was this answer helpful?
1
0

Concepts Used:

Magnetism & Matter

Magnets are used in many devices like electric bells, telephones, radio, loudspeakers, motors, fans, screwdrivers, lifting heavy iron loads, super-fast trains, especially in foreign countries, refrigerators, etc.

Magnetite is the world’s first magnet. This is also called a natural magnet.  Though magnets occur naturally, we can also impart magnetic properties to a substance. It would be an artificial magnet in that case.

Read More: Magnetism and Matter

Some of the properties of the magnetic field lines are:

  • The lines and continuous and outside the magnet, the field lines originate from the North pole and terminate at the South pole
  • They form closed loops traversing inside the magnet. 
  • But here the lines seem to originate from the South pole and terminate at the North pole to form closed loops.
  • More number of close lines indicate a stronger magnetic field
  • The lines do not intersect each other
  • The tangent drawn at the field line gives the direction of the field at that point.