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(a) Write the nature of path of free electrons in a conductor in the (i) presence of electric field (ii) absence of electric field. (b) Between two successive collisions each free electron acquires a velocity from 0 to v where v=(e E)/(m)tau. What is the avergae velocity of a free electron in the presence of an electric |
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Answer» SOLUTION :(a) (i) In the presence of electric FIELD, the paths of free electrons in a metal conductor are curved. (ii) In the absecnce of electice field, the paths of free electrons in a metal conductor are straight lines between two successive collisions. (b) Average velocity of a free electron in the presence of electric field is `v= (eE)/(m) tau` Where the symbols have their usual meanings. The different free electrons in a metal conductor move with differennt velocity in the presence of electric field. (C) As the temperature of a conductor increases, the thermal speed of the electrons incereases and also the amplitude of vibration of the metal atoms/ions increases. Now thr free electrons colide more frequently with the atoms/ions of metal. As a result of it, the VALUE of relaxation time `tau` decreases. Since average velocity`v PROP tau`, so the average valocity of free electrons decreases. |
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