Factors Affecting the Resistance of Conductors Flashcards
Name the four factors affecting resistance
Length
Cross Sectional Area (C.S.A)
Material
Temperature
How does length affect resistance
The length of conductor is proportional to the resistance assuming all other factors remain constant.
What is the relationship between length and resistance as a formula?
R1/R2 = l1/l2
R1 = resistance of a conductor 1
R2 = resistance of a conductor 2
l1 = the length of conductor 1
l2 = the length of conductor 2
How does Cross-Sectional Area affect resistance
The greater the cross-sectional area inversely proportional to the value of resistance.
The greater CSA the lesser the resistance.
What is the relationship between Cross-Sectional Area and Resistance?
R1/R2 = A2/A1
R1 = the resistance of a conductor 1
R2 = the resistance of a conductor 2
A1 = the cross-sectional area of conductor 1
A2 = the cross-sectional area of conductor 2
or to say that resistance is inversely proportional
R2 = R1 (d1/d2)2
d1 = the diameter of conductor 1
d2 = the diameter of conductor 2
How does conductor material affect resistance?
The chemical properties of the material changes its resistivity. The greater the resistivity, the greater the resistance.
What is the relationship between resistance and resistivity of the conductor material?
R = (pl)/A
R= Resistance
p = Resistivity
l = Length of conductor
A = C.S.A
How does Temperature affect resistance?
As the value of temperature increases, resistance increases for materials that have a Positive Temperature Coefficient (PTC).
Materials with a Negative Temperature Coefficient (NTC) losses resistance for greater temperatures (materials such as carbon, silicon, germanium).
What is the relationship between Resistance and Temperature?
Rh = Rc (1+aT)
Rh = the final resistance
Rc = the initial resistance
α = the temperature coefficient of resistance
T = the change in temperature
