Question

Assume the following: North is in front of you, South is behind you, East is to your right and West is to you left. An electron is moving at 2.0 x 107 m/s West. The earth's magnetic field is 0.0015-T and points upward. What is the magnitude of the force on the electron?

Answer: x 10^-15 N

The direction of the force is (N, S, E or W)?

Answer:  

Answer 1

Solution:

Force exerted on the charge q in a magnetic field, B is given by:

here, q= charge on the electron = 1.6 x 10^-19C

B= magnetic field of the earth = 0.0015 T

v= velocity of the electron= 2.0 x 10⁷ m/s West

and = angle between magnetic field B and velocity v= 90^o

Substituting the values in the above expression, we have,

F= 1.6 x 10^-19 X 2.0 x 10⁷ X 0.0015 X sin90^o

Therefore, F= 4.8 x 10^-15 N

The direction of force is towards North.