A uniform electric field and a uniform magnetic field exist in a region in the same direction. An electron is projected with a velocity pointed in the same direction. Then the electron will

Question

A uniform electric field and a uniform magnetic field exist in a region in the same direction. An electron is projected with a velocity pointed in the same direction. Then the electron will (A) be deflected to the left without increase in speed (B) be deflected to the right without increase in speed (C) not be deflected but its speed will decrease (D) not be deflected but its speed will increase

Tardigrade Admin · Accepted Answer

As the electron is moving parallel to both the fields, so magnetic force does not affect the electron's motion but electric force (qE) acts opposite to the motion of the electron. Hence, the electron will not be deflected but its speed decreases.

Q. A uniform electric field and a uniform magnetic field exist in a region in the same direction. An electron is projected with a velocity pointed in the same direction. Then the electron will

be deflected to the left without increase in speed

be deflected to the right without increase in speed

not be deflected but its speed will decrease

not be deflected but its speed will increase

As the electron is moving parallel to both the fields, so magnetic force does not affect the electron's motion but electric force $(qE)$ acts opposite to the motion of the electron. Hence, the electron will not be deflected but its speed decreases.