1 The magnitude of Earths magnetic field is about 05 G near

1. The magnitude of Earth\'s magnetic field is about 0.5 G near Earth\'s surface.
Part A
What\'s the maximum possible magnetic force on an electron with kinetic energy of 1keV?
Fm = N
Part B
Compare with the gravitational force on the electron.
Express your answer using two significant figures
Fg/Fm =

2. What is the current in a long wire if the magnetic field strength 1.2 cm from the wire\'s axis is 71 T ?
Express your answer using two significant figures.
I= A

Please answer both\'

thank you !

Solution

1. F = qvB

KE = 0.5*mv^2

F = qB*sqrt(2*KE/m)

Fm = 1.6*10^-19*0.5*10^-4*sqrt(2*10^3*1.6*10^-19/(9.1*10^-31)) = 1.5*10^-16 N

Fg = mg = 9.1*10^-31*9.81 = 8.92*10^-30

Fg/Fm = 8.92*10^-30/(1.5*10^-16) = 5.94*10^-14

2. magnetic field due to the wire is:

B = uo*i/2*pi*d

i = 2*pi*d*B/u0

i = 2*3.14*1.2*10^-2*71*10^-6/(4*3.14*10^-7)

i = 4.26 Amp.