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State Ohm's law and derive it from the b...

State Ohm's law and derive it from the basic ideas of drift velocity of electrons.

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Ohm.s Law : It states that potential difference across the two ends of a conductor is directly proportional to the current through it provided physical conditions (like temperature, pressure etc.) remain same.
Drift velocity of clectrons :
We know that
`v_d = (eEtau)/m " "...(1)`
and `I = nAe v_d " "...(2)`
But `E = V//l`
`implies v_d = (EVtau)/(ml)`
Put value of `upsilon_d` in eqn. (2)
`I=nAe((eVtau)/(ml))`
`I = ((nAe^2tau)/(ml))V`
we have `R=(ml)/(nAe^2tau)=a` constant
`implies I=V/R`
V = IR
`implies V prop I`
which is ohm.s law .
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