Changing Resistance

1. Jul 9, 2007

BMWPower06

1. The problem statement, all variables and given/known data
You have a tungsten wire with a certain length and cross-sectional area. This wire has a resistance R. If you wanted to make a new wire with a SMALLER resistance, which of the following changes would accomplish that objective?
True False use a piece of copper wire instead, with the same length and cross-sectional area
True False increase the temperature of the wire
True False use a thicker piece of tungsten wire, with the same length
True False use a longer piece of tungsten wire, with the same cross-sectional area
True False decrease the voltage between the ends of the wire

2. Relevant equations
V=IR
R=p(L/A)

3. The attempt at a solution
My answers are in bold, atleast one of them is wrong, but i do not know which one, can anyone help out?

1. Copper wire has a lower p so the R will be lower
2. Increasing Temp, increases the R
3. Increases A, which decreases R
4. Increases L which increases R
5. R=V/I so a lower V would mean a smaller R

I cant figure out which answer is wrong, any help?

2. Jul 10, 2007

BMWPower06

Anyone know what im doing wrong?

3. Jul 10, 2007

Dick

Think really hard about 5) again. Decreasing V decreases I, not R.