Cyclotron resonance

  • #1

Homework Statement


Calculate the lower limit of the electron scattering time in a material placed in a magnetic field of 1 T which is necessary to observe cyclotron resonance. The electron effective mass in the material
is 0.06 ##m_o## (where ##m_o## is the free electron mass).


Homework Equations


##\omega_c=\frac{eB}{0.06m_o}##
##\tau_{min}=\frac{2\pi}{\omega_c}##

The Attempt at a Solution


So I basically substituted values into ##\omega_c## and then into the equation for ##\tau_c## i got ##\tau_c=2.14ps## whereas the answer says ##\tau_c=0.54ps##, have I gone wrong? or is the solution given wrong, because i have done it multiple times.
 

Answers and Replies

  • #2
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The two answers differ by a factor of 4 (+-2%). I guess they took 1/4 of a cycle to be sufficient (some electrons won't scatter for 4 times the scattering time). There is no absolute limit, a shorter time just makes observations harder.
 
  • #3
ah okay! Thankyou very much I did notice the factor of 4 difference just wasn't sure where it came from.
 

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