Question

The aurora is caused when electrons and protons, moving in the earth's magnetic field of ≈5×10−5 T, collide with molecules of the atmosphere and cause them to glow. What is the radius of the circular orbit for (a) an electron with speed 1.0×106m/s and (b) a proton with speed 7.0×104m/s . What is re in meters and what is rp in meters?

Answer 1

You can use this,

qvB = (mv^2)/r

Answer 2

remember that
\[e=1.602x10^{-19}C\]
\[q_p = +e\]
\[q_e=-e\]

And be sure to keep track of units.

units on the magnetic field
\[1 T = \frac{1 kg}{s^2A}\]
and an Ampere can be written as
\[1 A = \frac{1C}{s}\]