# Homework Help: Potential Gradient of potentiometer wire

1. Jun 11, 2017

### Tanishq Nandan

1. The problem statement, all variables and given/known data
The resistivity of a potentiometer wire is (40×10^-8) ohm-m and the area of cross section is (8×10^-6)m^2.If 0.2 amp current is flowing through the wire,then the potential gradient will be??

2. Relevant equations
1.Resistance=[(Resisitvity)×(Length)]/(Cross-sectional area)
2.V=IR
3.Potential gradient of wire= (Potential difference across wire)/(Length of wire)
3. The attempt at a solution
▪Assuming the length of the wire to be l, and using formula 1,we can find the resistance of the wire.
▪Using formula 2,potential difference across the wire can be found,since we know the current flowing through the wire(which will obviously come in terms of l).
▪Using formula 3,we can get the value of potential gradient.
Problem:My answer is coming 1Vm^-1 whereas the answer given is 0.01Vm^-1
IF THE ANSWER GIVEN SEEMS TO BE WRONG,KINDLY REPLY SO.

2. Jun 11, 2017

### willem2

You use the right method, but your answer is wrong. Are you sure you have all units in meters?

3. Jun 11, 2017

### Tanishq Nandan

Yeah,they are in meters,but don't worry about it.I got it just now,had been commiting a silly mistake(blunder,crime,punishable by death).Simple calculation error. (I wrote 10^-8 divided by 10^-6 as 1,whereas it should have been 0.01).
But,thanks anyway!!