Question

An electron beam is moving vertically upward. If it passes through a magnetic field which is directed from south to north in a horizontal plane, then in which direction will the beam deflect.

Answer 1

Let us first get some idea about the Electron beam rule. Electron beam, a stream of electrons generated by heat (thermionic emission), bombardment of charged atoms or particles (secondary electron emission), or strong electric fields (as from a betatron) (field emission).

Complete answer:
Let us get some knowledge about Fleming left hand rule. When a current-carrying conductor is exposed to an external magnetic field, it is subjected to a force that is perpendicular to both the field and the current flow direction. John Ambrose Fleming was the one who came up with the idea. In this rule a left hand may be held in such a way that the thumb, forefinger, and middle finger serve three mutually orthogonal axes.

When the thumb, centre finger, and forefinger of the left hand are arranged at right angles to one another, the thumb points in the direction of magnetic power, the centre finger points in the direction of current, and the forefinger points in the direction of a magnetic field.

So, the magnetic field is from south to north, and electrons are travelling upwards, but we can consider the conventional direction, which is downwards, so we can deflate the beam to the west using the left hand thumb law.

Note: Let us get more knowledge about electron beams. Cathode rays (also known as electron beams or e-beams) are electron streams seen in vacuum tubes. A directed beam of electrons deflected by electric or magnetic fields in cathode ray tubes creates the picture in a traditional television set (CRTs).