Magnetic Force on Current & Moving Charges

Understanding Magnetic Force

When a charged particle moves through a magnetic field, it experiences a force. This force is known as the magnetic force. The force depends on the charge of the particle, its velocity, and the magnetic field strength.

The formula to calculate the magnetic force on a moving charged particle is:

$$F = qvB$$

• F is the magnetic force (in newtons, N)
• q is the charge of the particle (in coulombs, C)
• v is the velocity of the particle (in meters per second, m/s)
• B is the magnetic field strength (in teslas, T)

Direction of Magnetic Force

The direction of the magnetic force is determined by the right-hand rule. For a positive charge:

• Point your thumb in the direction of the velocity (v).
• Point your fingers in the direction of the magnetic field (B).
• Your palm will face the direction of the force (F).

For a negative charge, the force direction is opposite to the direction indicated by your palm.

Magnetic Force on a Current-Carrying Wire

A current-carrying wire in a magnetic field also experiences a force. The force can be calculated using:

$$F = ILB$$

• I is the current in the wire (in amperes, A)
• L is the length of the wire in the magnetic field (in meters, m)
• B is the magnetic field strength (in teslas, T)

Worked Example