# Question involving resistivity using the formula?

1. Apr 1, 2012

### einstein101

1. The problem statement, all variables and given/known data

The resistivity of nichrome wire is 1.1micro ohm meters. What length of wire of diameter 0.079 mm is required to provide resistance of 1.0 Kohm?

2. Relevant equations
R=resistivity x length/area

3. The attempt at a solution

1000ohms = ? x 0.0011/0.079

79 = ? x 0.0011

71818.18 = resistivity

I know I've stuffed up real bad, but this one is troubling me crazy.

2. Apr 2, 2012

### ehild

What does "area " mean in the formula for resistance? What is the area for the 0.079 mm wire?

ehild

3. Apr 2, 2012

### einstein101

Area relates to the 0.079 mm of wire. In the question it doesn't say mm squared. the answer is supposed to be 4.5 meters.

4. Apr 2, 2012

### ehild

The diameter of the wire is 0.079 mm. The cross-section of a wire is a circle usually. The area in the formula means the area of the cross section of the wire.

ehild

5. Apr 2, 2012

### Emilyjoint

I got 4.5m for the length.
I think you have mixed up the units.
resistiuvity = 1.1x10^-6ohm.metre

6. Apr 2, 2012

### einstein101

Thanks Emily I got the answer too now. You were right I was mixing the units up.

7. Apr 3, 2012

### Emilyjoint

Hey Einstein....thanks...great help someone else