1. A fixed resistor A filament lamp An LED Sketch an I/V graph for:
Now underneath sketch R/V graphs for:

2. Resistivity
01/08/2018
LO:
Investigate how resistance varies with length and cross-sectional area
Define resistivity and practice using the formula

3. Investigation
Connect the thin wire in series to a 1.5V battery.
Measure its pd & the current through it. Calculate resistance. Repeat for the thicker wire.
Conclusion – How does resistance vary with cross-sectional area (A)? Use a proportional sign.
2) Connect one of the wires to a 1.5V battery. Measure
current at varying lengths (l) of wire and calculate
resistance(R) for each. Plot a graph of resistance (y-axis) against length (x-axis).
Conclusion -How does resistance vary with length (l)? Use a proportional sign.

4. Where:
R is resistance in ohms,Ω
ρ is resistivity in ohm metres,Ωm
L is length in metres,m
A is cross-sectional area in m2

5. Resistivity is a measure of how strongly a material opposes the flow of electric current. A low resistivity indicates a material that readily allows the movement of electric charge.
Resistance is a property of a sample of material E.g. A certain piece of copper wire
Resistivity is a property of a material
E.g. Copper

6. 2.85Ω E.g. Coppers resistivity is 1.68x10-8Ωm at 20oC.
What is the resistance of a sample of copper that is 3.00m long and has a diameter of 0.15mm?
2.85Ω

7. Practice makes perfect!
AS Electricity Specimen Questions
Questions Pg 103
Resistivity Worksheet (not qu7)

8. How does the resistivity of conductors vary with temperature? Why?