A singly charged positive ion with a mass of 668 Times 1027

A singly charged positive ion with a mass of 6.68 Times 10^-27 kg moves clockwise in a circular path of radius 3.00 cm with a speed of 1.00 Times 10^4 m/s. Find the direction and strength of the magnetic field.

Solution

For circular motion,

the magnetic force must provide the necessary centripetal force

So, qvB = mv^2/R

So, B = mv/qR

where

m = 6.68*10^-27 kg

v = 1*10^4 m/s

q = 1.6*10^-19 C

r = 3 cm = 0.03 m

So, B = 6.68*10^-27*1*10^4/(1.6*10^-19*0.03)

So, B = 0.0139 T <------------magnitude

For clockwise motion,

the direction of magnetic field = out of the plane of circular motion of the charge