Answer to Question #101306 in Quantum Mechanics for Tosin

Question

An electron is emitted from the surface of the big metallic plane perpendicular to it with initial velocity 0 v , How far from the plane the electron may manage to move in two cases: 1) the electron moves in the braking electric field E , 2) additionally to the electric field E, there is a magnetic field B, directed parallel to the surface of the plane

Answer 1

1)

the kinetic energy of the electron is numerically equal to the work of the forces of the electric field

$\frac{mv^2}{2}=eEd (1)$

Where m is the mass of electron, e is the charge of electron

Using (1) we get

$d=\frac{mv^2}{eE}$

2) the magnetic force is always perpendicular to the direction of displacement and magnetic forces do not do any work

$d=\frac{mv^2}{eE}$