Question

In a wire of cross section radius r, free electrons travel with drift velocity v when a current I flows through the wire. What is the current in the another wire of half the radius and of the same material when the drift velocity is 2v

Answer 1

Answer:

The current in the another wire of half the radius and of the same material when the drift velocity is 2v is I/2.

Explanation:

Here we are using the formula

current = neAv ...............(1)

 where n= number of electron density

A =area of cross section

e= charge of electron

v=drift velocity

As both the wires are of same materials then the electron density is same for both.

For the first wire, current I  is given by,  

I = neAv  

 Now according to the problem nother wire of half the radius and of the same material when the drift velocity is 2v

Therefore for the second wire current is = ne(A/4)(2v)

                                                                     = (neAv)/2

                                                          now putting I at this place

                                                                     = I/2

Answer 2

Explanation:

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