00:01
Okay, suppose that we have a copper wire of length l that has a resistance r of 10 oms.
00:09
The problem is, at what point along its length must the wire be cut so that the resistance of one piece is four times the resistance of the other.
00:20
And what is the resistance of each piece? so we can determine that using the formula for resistance, which is this, the product of resistivity and the length over the.
00:31
Sectional area.
00:35
Then isolating to the rights of the equation, the constants, which is the resistivity in the cross -sectional area.
00:45
Then for the two part, two cut parts, we have resistance of the short over the length of the short is equals to the resistance of the lung over the length of the long section, since they have the same resistivity over the concessional area.
01:12
Then isolating the length of the long to the left side of the equation we have this now since from our resistance equation we can see that the length is directly proportional to the resistance then the resistance of the long cut is four times the resistance of the shortcut so the one with longer length has a greater resistance then inserting in our equation we have this and you can see that the length of the long cut is also 4 times the length of the shortcut.
02:24
Since the again, the length is directly proportional to resistance...