Physics Group - II (3110018)

BE | Semester-1   Winter-2019 | 02-01-2020

Q3) (b)

Fermi energy of a given substance is 7.9 eV. What is the average energy and speed of electron in this substance at 0 K?

Fermi energy  EF   = 7.9 eV

Average energy   E0¯    = 35 EF  

Average energy   E0¯    = 35 × 7 . 9

Average energy   E0¯    = 4.47 eV  

Now, Speed of electron can be calculated:  E0¯    = 12 m V2  

  V =  2 E0¯m

  V =  2 × 4.74 × 1.6 × 10-199.1 × 10-31

  V =  1.2 × 106  m/sec