Question

An electron enters an electric field with its velocity in the direction of the electric lines of field then:
A. The path of the electron will be a circle
B. The path of the electron will be a parabola
C. The velocity of the electron will decrease just after entry
D. The velocity of the electron will increase just after entry

Answer 1

Hint: In electrostatics, an electric field is the area of influence around a charged particle such as an electron in which the charged particle can apply force on other charged particles or can interact if the other charges are there in that area. It has both magnitude and direction.

Complete step by step solution:
It is known that the field around a charged particle is represented by imaginary lines also known as electric field lines. These field lines were first discovered by a famous English scientist Sir Michael Faraday, in 1830 while performing an experiment in which he observed how iron filings arrange themselves when sprinkled around a magnet.

When an electron enters an electric field with some velocity, , the electric field lines apply a force on that electron. The force applied by the electric field will be in an opposite direction from that of the motion of electrons.

Since, the applied force and displacement are in the opposite directions, therefore, the velocity of the electron will decrease due to the electric field lines. So when an electron enters an electric field with its velocity in the direction of electric field lines then the velocity of the electron will decrease just after entry.

Therefore, Option C is the correct answer.

Note:It is to be noted that electric field lines originate from the positive charge and terminate at the negative charge. In a system, there will be a number of electric field lines which will never intersect each other at any point, because if they intersect then at the point of intersection, there will be two different directions of electric field which is not possible.