00:01
Hi there, so for this problem, we are told that the number density of three electrons in a cooper conductor is estimated to be equal to 8 .5 times 10 to the 28 meters to the minus 3 and and the question is how long does an electron take to drift from one end of a wire and the length of the wire is given that is three meters and to its other end.
00:36
Now, the area of the cross -ception is also given, the area of the conception of this wire, and that is equal to 2 times 10 to the minus 6 meters square, and is a current that is also given, and that current is equal to 3 -amper.
00:59
So with that said, what we need to calculate is the time, and for that we use the thought that the speed, the drift speed, can be written as the length divided by the time.
01:13
Now, and the drift speed is related with the current because the current is equal to the product between the density of free electrons, this times the charge of an electron, this times the cross -ceptional.
01:36
Area, this time the drift velocity.
01:38
Now we substitute this in here, so we will have the following.
01:43
And now we just need to simply solve for the time.
01:46
So the timing here is just simply the density, the charge of an electron, the corresponding area, the length, and this divided by the current.
01:55
And now we substitute these values, 8 .5 times 10 to the minus to the 28 per meter per cubic meter, this times the charge of an electron that we know is 1 .6 times 10 to the minus 19 in units of columns...