An electron enters a magnetic field as given in the fig.
a) what will be the direction of force acting on the electron ?
B) state the rule to determine the direction of the force
c) instead of electron a Proton enters the field. what will be its direction of motion ? why ?
Answers
The force is found by using F = i(l )( B) if the charge is at right angles to the magnetic field. Here i is the current, l is the length of the conductor and B is the magnetic field.
The force will be perpendicular to the direction of current and the magnetic field. For this you will use Fleming's left hand rule.
You need to remember that the direction of current is opposite to the direction of motion of electron.
I am assuming that the magnetic field is from left to right in the plane of the paper and the electron is moving from up to down , again in the plane of the paper.
Now point the fingers of your left hand so that your second finger points in the direction of current, your first finger points in the direction of the magnetic field, then your thumb will give you the direction of motion or force.
You can see that the thumb is pointing downwards into the page.
Try this and tell me if you still can find the direction. Since the exact directions were not mentioned in the question given by you, you can see that I have assumed directions for electron movement and magnetic field.