A `N`-type silicon sample of width `4xx10^(-3)m`, thickness and length `6xx10^(-2)m` carriers a current of `4.8mA`, when the voltage is applied across the length of the sample. The free electron density is `10^(22)m^(-3)`

Options

A. The current density is `20 A//m^(2)`
B. The drift speed is `1.25 cm//sec`
C. The time taken by electrons to travels the full length of the sample is `4.8`sec
D. All option are correct

Answer

D

Explanation

(a) `j=(i)/(A)=(4.8xx10^(-3))/(4xx10^(-3)xx6xx10^(-2))=20A//m^(2)`
(b) `j=n ev_(d)`
`v_(d)=(j)/(ne)=(20)/(10^(22)xx1.6xx10^(-19))`
`=1.25xx10^(-2)m//s=1.25 cm//sec`
(c ) `t=(l)/(v_(d))=(6xx10^(-2))/(1.25xx10^(-2))=4.8sec`