3. Here we have a band diagram shown below. Assume that each band has a shape given by the Feynman model. Choose a band gap of zero. a. Find the group velocity at the center of each band. b. Compare to the free electron velocity at the same k-value. c. Find the effective mass at the bottom of each band as a function of n. E 2v, 2v 12v A 77 a 27 a 3T a 3. Here we have a band diagram shown below. Assume that each band has a shape given by the Feynman model. Choose a band gap of zero. a. Find the group velocity at the center of each band. b. Compare to the free electron velocity at the same k-value. c. Find the effective mass at the bottom of each band as a function of n. E 2v, 2v 12v A 77 a 27 a 3T a