Posted by **Amber** on Friday, September 22, 2006 at 3:04am.

The resistance(r)of a wire varies directly as the length(L)of the wire and inversely as the square of the diameter(d). If the resistance is 9ohms in 50ft of wire that has a diameter of 0.05in, find the resistance in 50ft of a similar wire that has a diameter of 0.02in.

Resistance=constant*Length/diameter^2

Two ways you can work this:

1) In the equation, solve for the constant (you have resistance 9 ohms, Length 50, and diameter .05). Then use that constant in the equation to solve for the new conditions,

2) Notice the length is the same, however...

Resistance1=constant*Length1/diameter1^2

and

Resistance2=constant*Length2/diameter2^2

now dividing the second equation by the first, and noting that the length1 and length 2 are the same..

Resistance2/resistance1=(diameter2/diameter1)^2

or resistance2=resistance1(diameter2/diameter1)^2

## Answer This Question

## Related Questions

- Math - The electrical resistance of a wire waves directly as its length & ...
- college algebra - The electrical resistance of a wire of a given material varies...
- algebra - A three quarter inch wire has 12 ohms resistance. How much resistance ...
- Algebra joint, inverse and direct variation - Urgent! If t varies inversely as ...
- Algebra II - The resistance of a wire is inversely proportional to the square of...
- Algebra - If t varies inversely as the cube of z and directly as the square of r...
- Algebra - If t varies inversely as the cube of z and directly as the square of r...
- Physics - A nichrome wire of diameter 5mm and length 5m has resistivity of 10^-4...
- Physics - Two wires with the same resistance have the same diameter but ...
- Math - If 750 m of 3.00-mm-diameter wire has a resistance of 27.6, what length ...

More Related Questions