Question

If a charge projected in a zero gravity region. find possible cases of electric and magnetic field in that region so no net force exerts on charge.
A) E =0 B=0
B) E=0 B not equal to 0
C) E not equal to zero B not equal to zero
D) E not equal to zero B=0

Answer 1

Given:

A charge is projected in a zero gravity region.

To find:

Possible cases of Electric and Magnetic Field.

Solution:

The following cases are possible:

• E = 0 , B = 0

• E = 0 , $B\neq 0$

• $E \neq 0 \:and \:B \neq 0$

Reasons:

• In the 1st case , if both electrostatic and magnetic field intensity is zero then no net force acts on the charge. As a result, the charge moves with constant velocity.

• In the 2nd case , only magnetic field intensity is present. The magnetic field intensity has to be directed towards the direction of velocity such that no force is experienced.

• In the 3rd case, there is presence of both electrostatic and magnetic field intensity. For example: electrostatic field intensity will be directed upward and magnetic field intensity will be directed out of the plane of the paper. This will lead to cancellation of electrostatic and magnetic force. Hence net force becomes zero.

Refer to the attached diagram for the 3rd case.