Electrical Maths Questions

• September 21st 2008, 10:48 PM
J4553
Electrical Maths Questions
Well, 3 questions actually. See below.

• September 22nd 2008, 03:32 AM
CaptainBlack
Quote:

Originally Posted by J4553
Well, 3 questions actually. See below.

For question 3 you are told that the resistance varies linearly with length and inversly as the square root of the diameter. That means there is a constant $k$ (other things being equal) such that:

$R=\frac{k l}{\sqrt{d}}$

You are given the resistance, 30.9 Ohms of a 850 mm length of 0.122 mm diameter wire so:

$k=\frac{30.9\sqrt{0.122}}{850}$

when resistance is given in Ohms and length and diameter in mm.

Now you know $k$ you can use the first equation to find the resistence of any wire of the same material.

RonL