Simple drift speed probem driving me nuts

[ttran1117]

Homework Statement

A current of 200 mA flows in a silver wire of radius 0.8mm. Find (a) the drift speed of the electrons. (b) the number density of particles.

Homework Equations

The Attempt at a Solution

The answer in the book is 1.07 x 10^-5, but I'm getting 1.06 x 10^-4. Can anyone tell me what I'm doing wrong?

So, I have J = I/A and J=nev_d ==> v_d = J/(ne)
J = 200 x 10^-3/pi(0.8x10^-3)^2

n = p*Avg/M
= 1.05 * 6.022 x 10^23 / 107.868 x 10^-3

plugging in for v_d, I get 1.06 x 10^-4.

This problem is supposed to be simple, but it's driving me nuts! Someone help please! Thanks a lot

 

[ehild]

You used wrong value for the density of silver.

ehild