Question
Question: An electron is projected with uniform velocity along the axis of a current carrying long solenoid. W...
An electron is projected with uniform velocity along the axis of a current carrying long solenoid. Which of the following is true?
A
The electron will be accelerated along the axis
B
The electron path will be circular about the axis.
C
The electron will experience a force at 45° to the axis and hence execute a helical path.
D
The electron will continue to move with uniform velocity along the axis of the solenoid.
Answer
The electron will continue to move with uniform velocity along the axis of the solenoid.
Explanation
Solution
Let the electron (e) is projected with a uniform velocity (v) in a uniform magnetic field B. The magnitude of force on it is
As 
Hence the electron will continue to move with a uniform velocity along the axis of the solenoid