An electron in a magnetic field has a cyclotron frequency of

An electron in a magnetic field has a cyclotron frequency of 6.0 x 1012 Hz. What is the magnetic field strength? (The mass of an electron is 9.1 x 10-31 kg, and the charge of an electron is 1.6x 10-19 C) A) 6.0 T B) 210 T C) 0.00471T D) 0.17T

Solution

The cyclotron frequency is given by:
f = B*q/(2*pi*m)

B = 2*3.14*9.1*10^-31*6*10^12/(1.6*10^-19) = 214.305 T

Nearest possible answer is 210 T (option B)