Purpose: To demonstrate that charged particles (electrons) are deflected by a magnetic field.

The apparatus consists of an induction coil, a 6-V power supply, and a cathode ray tube connected as shown in the diagram below.

The discharge tube contains a luminescent screen positioned such that the beam strikes it and is clearly visible over a distance of approximately 15 cm. A bar magnet is included to provide the deflecting B field.

A beam of electrons is set up in the discharge tube, and the magnet is brought up to the beam so that the magnetic field is perpendicular to the velocity of the electrons. Reversing the direction of the magnet naturally reverses the direction of the beam deflection.

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