Force on a current-carrying conductor

1. Set up a strong horseshoe magnet with the poles facing horizontally.
2. Suspend a straight length of wire (approximately 7.2 cm) horizontally between the poles of the magnet, so it is perpendicular to the magnetic field. This can be done using thin, flexible wires connected to a power supply.
3. Connect the wire in a circuit with a power supply, ammeter and a switch.
4. Close the switch and observe the movement of the wire. The wire will be deflected upwards or downwards due to the force acting on it.
5. To demonstrate the effect of reversing the current, reverse the connections to the power supply. Observe that the wire now deflects in the opposite direction. The direction of the force on the wire changes when the current is reversed.

(a) When the direction of the current is reversed, the direction of the force on the conductor is also reversed. The force acts in the opposite direction.
(b) When the direction of the magnetic field is reversed, the direction of the force on the conductor is also reversed. The force acts in the opposite direction.

Force, F = BIl
F = 0.25 T * 8.0 A * 0.1 m
F = 0.2 N

The formula F=BIl is used to calculate the force on a current carrying conductor in a magnetic field. B is magnetic field strength, I is current, and l is length of conductor in the field.

The force is upwards.

This can be determined using Fleming's Left Hand Rule. Point your index finger in the direction of the magnetic field (into the page), your middle finger in the direction of the current (left to right), and your thumb will point in the direction of the force (upwards).

Force on a single electron is given by F = Bqv, where B is the magnetic field strength, q is the charge, and v is the velocity.
F = (0.1 T) * (1.6 x 10^-19 C) * (2.0 x 10^7 m/s) = 3.2 x 10^-13 N. The force is 3.2 x 10^-13 N. This calculation uses the formula for the magnetic force on a moving charge.

The direction of the force is upwards. Applying Fleming's Left Hand Rule (or the right-hand rule for positive charges), with the magnetic field (middle finger) pointing into the page and the current (forefinger) pointing to the right, the force (thumb) points upwards. Thus, the beam deflects upwards.