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A potential barrier of 0.7V exists across a p-n junctionIf the depletion layer is 7.0xx10^(-7)m thick, what is the intensity of the electric filed in this region?If an electron is approaching the p-n junction from the n-side with a speed 6.0xx10^(5)ms^(-1), determine the speed with which it enters the p-side of p-n junction.

Answer»

SOLUTION : Here, `V_B=0.7V,d=7.0xx10^(-7)m`
Intensity of electric field in the REGION of depletion layer,
`E=V_B/d=(0.7)/(7.0xx10^(-7))=1.0xx10^(6)V//m`
Here, `v_(1)=6.0xx10^(5)ms^(-1)`, LET `v_(2)` be the velocity with which electron ENTERS the p-region. Then
`1/2xx9.1xx10^(31)xx(6.0xx10^(5))^(2)`
`=(1.6xx10^(-19))xx0.7+1/2xx9.1xx10^(-31)xxv_(2)^(2)`
`1.64xx10^(-19)=1.12xx10^(-19)+(9.1xx10^(-31))/2v_(2)^(2)`
On solving, `v_(2)=3.4xx10^(5)ms^(-1)`


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