resistance, wire, btec

1. Resistance
of a wire

2. A
l
R



3. Definitions
• Electrical resistance is a measure of the
opposition to the flow of electric charge
• Resistivity is a measure of how strong a
material resists the flow of electric charge
• Length is the distance between two end of a
wire
• Area for a circular wire is 𝐴 = 𝜋𝑟2

4. A
l
R


R
lR 
A
R
1


6. Hypothesis
• If I increase the resistivity of the wire, then
the resistance will increase
• If I increase the length of a wire, then the
resistance will increase
• If I increase the area of a wire, then the
resistance will decrease
• (If I increase the reciprocal of the area of a
wire, then the resistance of a wire will
increase)

7. Method
• What will I change? This is your independent
variable
• What will I measure? This is your dependent
variable
• What will you keep the same? This is
everything else!