what is k?

Question

The resistance Rof a wire varies directly with its length Land inversely with the square of its diameter d.
Write an equation for the constant of variation in terms of R,L,and d.Use kas a constant of proportionality.

Answer 1

The longer a wire is, the more resistance it has, this should be intuitive.

Thinker wires have less resistance - this is not intuitive, but think if it has having two haves that are parallel, which cuts the resistance in half.

 

Let L be the length of a wire, d represent the diameter, and some constant k represent how many times some unit of length.

 

Let R be the resistance of the wire.