Question

A uniform magnetic field exists in the plane of paper pointing from left to right as shown in Figure. In the field an electron and a proton move as shown. The electron and the proton experience

विकल्प

• forces both pointing into the plane of paper

• forces both pointing out of the plane of paper

• forces pointing into the plane of paper and out of the plane of paper, respectively

• force pointing opposite and along the direction of the uniform magnetic field respectively

Answer 1

forces both pointing into the plane of paper

Explanation - 

The direction of the current is taken as opposite to the flow of electron or in the direction of the flow of protons.

In the given figure, the proton and electron are moving in the opposite direction to each other and perpendicular to the direction of the magnetic field. So, current due to both electron and proton are in the same direction. Hence, the forces acting on both will be in the same direction. By Fleming's left-hand rule the direction of force is pointing into the plane of the paper.