Solve the follwing example .
An electron enters a magnetic field at right angles to , it as shown in figure 13.36

The direction of force acting on the electrons will be …….

Options

A. to the right
B. to the left
C. out of the page
D. into the page .

Answer

d

Explanation

According to the give figure , the magnetic filed is unifrom and directed from left to right horizontally in the plane of paper .
The electron moves perpendicular to the magnetic field in vertically downward direction and in the plane of paper .

The direction of the convential current is opposte to the direction of the conventional current is opposite to the direction of motion of the electron . The current is therefore upward in the plane of paper .
Application of Fleming.s left - hand rule shows that the direction of the fore acting on the electron will be perpendicular to the plane of paper , into the page (see figure13.37).