A molecule of a gas, filled in a discharge tube, gets ionized when an electron is detached from it. An electric field of 5.0 kV m–1 exists in the vicinity of the event.

(a) Find the distance travelled by the free electron in 1 μs assuming no collision.


(b) If the mean free path of the electron is 1.0 mm, estimate the time of transit of the free electron between successive collisions


a) Given electric field E= 5 kV m-1 = 5×103 V m-1


Time t=1 μs = 1×10-6 s.


Let m be the mass of electron and q be the charge of electron where m=9.1×10-31 kg


q =1.6×10-19 C


We know,





where F is the force, E is the electric field strength and q is the


magnitude of charge.


Also, distance travelled by an electron is


(as initial velocity is 0)





b) Here mean free path S travelled by electron is given as S=1mm


=10-3 m


We know,



Also,







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