Question

The magnetic moment of a magnet of length 10 cm and pole strength $4.0Am$ will be
(A) $0.4A{m^2}$
(B) $1.6A{m^2}$
(C) $20A{m^2}$
(D) $8.0A{m^2}$

Answer 1

Hint: Use the equation for a bar magnet's magnetic moment. The relationship between the magnet's pole strength and the separation between its poles is provided by this formula. Review the fundamentals of a magnet's pole strength, then observe whether it changes after being severed. Then determine the new magnetic moment of either cut component as well as the new length of the magnet's sliced sections.

Formula used:
The formula for the magnetic moment is M=ml, where l stands for the magnet's length, M stands for the magnetic moment and m stands for the pole strength of the magnet.

Complete step by step solution:
Magnet moment is a vector quantity. The magnetic moment vector frequently aligns with the magnetic field lines when the objects are positioned in that way.

The magnetic moment of a magnet points from its south pole to its north pole. A magnet's magnetic moment is inversely proportional to the magnetic field it produces.

The sum of the pole strengths and the separation between the two poles is known as the magnetic dipole moment. The magnet length, or 2l, is the distance between a magnet's two poles or a magnetic dipole.

Given in the question;
Pole strength is $4.0Am$ .
Length of the magnet is 10 cm.

Now, magnetic moment when the length and the pole strength of a magnet is given:
$M = mL$
Where, m is the pole strength of the magnet.
L is the length of the magnet.

From the question, putting all the values;
$M = 4 \times 10 \times {10^{ - 2}}$
$M = 0.4A{m^2}$

Hence the correct answer is Option(A).

Note: In the simplest words possible, a magnetic moment can be described as a vector with both direction and magnitude. A magnet's magnetic moment travels in a straight line from its south pole to its north pole. Every magnet has two poles, the North Pole and the South Pole, as you are all aware.