Saved Bookmarks
| 1. |
An N-type silicon sample of width 4 xx10^(-3)m thickness 0.25mm and length 6 xx10^(-2) m carries a current of 4.8 mA when the voltage is applied across the length of the sample. What is the current density? If the free electron density is 10^(22) m^(-3) , then find how much time it takes for the electrons to travel the full length of the sample. |
|
Answer» SOLUTION :The CURRENT density J is given by `J= (I )/(A )= ( 4.8 xx 10^(-3))/(( 4 x 10^(-3)) ( 25xx 10^(-5)) )= ( 4.8 xx 10^(-3))/( 10^(-6))` The drift velocity `v_d` is given by `v_d = (J )/( n e)= ( 4800)/( 10 ^(22) xx 1.6 xx 10^(-19))= 3m//s` The timetakent isgivenby `t=(L )/(u_d ) =( 6 xx 10^(-2))/( 3 ) = 0.02sec ` |
|