Question

A proton moves with a speed of 1.17 105 m/s through Earth's magnetic field, which has a value of 50.0 µT at a particular location. When the proton moves eastward, the magnetic force acting on it is directed straight upward, and when it moves northward, no magnetic force acts on it.

(a) What is the direction of the magnetic field?

(b) What is the strength of the magnetic force when the proton moves eastward? ?N

(c) Calculate the gravitational force on the proton and compare it with the magnetic force. Compare it also with the electric force if there were an electric field with magnitude E = 1.50 102 N/C at that location, a common value at Earth's surface. Note that the mass of the proton is 1.67 10-27 kg. Fgrav = N Felec = N

Suppose an electron is moving due west in the same magnetic field as in the example at a speed of 2.95 105 m/s. Find the magnitude and direction of the magnetic force on the electron. F = ?N

Answer 1

a) Southward you need to apply right hand rule. If you close your hand to the east, your thumb will indicate south.

b) Given the equation for Magnetic Force

`F= qVB`

Replacing

`F= (1.16*10^(-19))(1.17*10^5)(50*10^(-6))`

`F=9.36*10^(-19)`

c) Given the second Newton's Law by

`F_g = 1.67*10^(-27)*9.81`

`F_g = 1.64*10^(-26)`

Given the electric force by,

`F_e = 1.6*10^(-19)*1.5*10^2`

`F_e = 2.4*10^(-17)N`

`F=9.36*10^(-19)N`