Magnetic Forces, Materials, and Devices - Questions With Answers (Short Notes)


01. State Three Ways In Which Forces Due To Magnetic Fields Can Be Experienced?

Answer: There are at least three ways in which force due to magnetic fields can be experienced. The
force can be

  • due to a moving charged particle in a magnetic field.
  • on a current element in an external magnetic field.
  • between two current elements.

02. State The Lorentz Force Equation?

Answer: The Lorentz force equation relates the force acting on a particle with charge Q in the presence of EM fields. It expresses the fundamental law relating EM to mechanics.

F = Q(E + u * B) = m ( du/dt)

Based on the Lorentz force law, the force experienced by a current element Idl in a magnetic field B is
dF = I dl * B

From this, the magnetic field B is defined as the force per unit current element.


03. Define Magnetic Torque?

Answer: The torque T (or mechanical moment of force) on the loop is the vector product of the force F and iho moment arm r.

T = r X F
and magnetic torque is measured in Newton-meters (N • m).

Magnetic torque on a current loop with magnetic moment m in a uniform magnetic field B is

T = m * B 


04. What Is The Magnetic Dipole Moment?

Answer: The magnetic dipole moment is the product of current and area of the loop; its direction is normal to the loop.
T = m * B
where,
T is the magnetic torque
m is the magnetic dipole ( A/m2)
B is the magnetic field

A magnetic dipole is a bar magnet or a small filamentary current loop; it is so called due to the fact that its B field lines are similar to the E field lines of an electric dipole.


05. State The Comparison Between Electric & Magnetic Monopoles & Dipoles?

Answer:




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