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what is relaxation time ?derive an expression for resistivity of a wire in terms of member density of free electrons and relaxation time .

what is relaxation time?derive an expression for resistivity of a wire in terms of member density of free electrons and relaxation time.

Grade:12

13 Answers

Sanandanan M
38 Points
12 years ago
Relaxation time is the time interval between two successive collisions of electrons in a conductor, when current flows.
I = nave --> n->no. of free electrons a->area of conductor v->drift velocity e->charge of electron
but v=(eE/m)T-->  E-> field m->mass of electron T->Relaxation time
From this, you can find expression of relaxation time.Field is V/length and V=IR.From this you can modify the expression in terms of resistivity.
G Narayana Raju
51 Points
12 years ago

i am sorry that was the correct ans

sofie sajad
19 Points
7 years ago
Relaxation time is actually a time constant that describes the rate of decay of charges inside the conductor.
Abhishek Ranjan
11 Points
6 years ago
Let us suppose that we have a solid metal ball or sphere and you placed a charge inside it. This charge will arrive at the surface as a surface charge. How fast this charge arrives at the surface can be calculated by using the term relaxation time.
The charge we kept inside the ball repel each other to arrive at the surface. Time taken by charges to travel to the surface s represented by relaxation time.
Sohan Js
26 Points
6 years ago
If Electric field is turned OFF suddenly the average velocity decreases exponentially. The decay of average velocity is given by 
vavg =vavge-t/tr  
At  t=tr
vavg=vavge-1
 
Relaxation  time can be defined as the time taken by electron to attain an average velocity which is 1/e times its value.
Deepak
11 Points
6 years ago
Relaxation time :It is the time between 2 successive collisions of an electron with atoms/ions of the conductor
Zuhaib
34 Points
5 years ago
The average time interval between two successive collisions is called relaxation time of electrons.
Yash
15 Points
5 years ago
 
 
The average time between successive collison of an electron is called relaxation time . During the relaxation time ,electron gain average velocity.
 
 
 
 
 
 
mohit
13 Points
5 years ago
average time taken by electron to attain steady state from zero velocity in presence o electric field.
Krish Gupta
askIITians Faculty 82 Points
3 years ago
 
If Electric field is turned OFF suddenly the average velocity decreases exponentially. The decay of average velocity is given by 
vavg =vavge-t/tr  
At  t=tr
vavg=vavge-1
 
Relaxation  time can be defined as the time taken by electron to attain an average velocity which is 1/e times its value.
Krish Gupta
askIITians Faculty 82 Points
3 years ago
You can think it intuitively as well.Let us suppose that we have a solid metal ball or sphere and you placed a charge inside it. This charge will arrive at the surface as a surface charge. How fast this charge arrives at the surface can be calculated by using the term relaxation time.The charge we kept inside the ball repel each other to arrive at the surface. Time taken by charges to travel to the surface s represented by relaxation time.
Krish Gupta
askIITians Faculty 82 Points
3 years ago
Relaxation time : Relaxation time is actually a time constant that describes the rate of decay of charges inside the conductor.
Krish Gupta
askIITians Faculty 82 Points
3 years ago
Or more easily defined as, The average time interval between two successive collisions is called relaxation time of electrons.

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