Why is the value of drift velocity so small?

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Solution

Dear Student,

The electron drift velocity is the average velocity that an electron, attains due to an electric field. Due to the collision between the electrons, the average velocity ie electron drift velocity is very small.

alternatively,

I=venA where v=drift velocity, e=charge on electron, n=no. of electrons and A=area of cross section.

$F o r a c o n s \tan t c u r r e n t i n a f i x e d c o n d u c t o r (c o n s t a r e a o f c r o s s s e c t i o n) v = (\frac{I}{e A}) \times \frac{1}{n} o r v \propto \frac{1}{n} S o a s t h e n u m b e r o f e l e c t r o n s i n c r e a s e s t h e d r i f t v e l o c i t y r a p i d l y d e c r e s e s i f t h e c u r r e n t i s h i g h n u m b e r o f e l e c t r o n s w i l l b e v e r y h i g h h e n c e t h e d r i f t v e l o c i t y w i l l b e v e r y l o w .$

Regards.

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