Resistance Flashcards
What is resistance
Opposition to current flow
What is resistance measured in?
Ohms (
Name some insulators
Wood
Paper
Rubber
Mica
Insulating varnish
Porcelain
Plastic
Woven fabrics
Glass
Name some conductors
Copper
Brass
Silver
Carbon
Salt water
Aluminium
Platinum
Mercury
Gold
What four factors affect resistance of a conductor
Material
Length of conductor
Cross sectional area
Temperature
Why does the length of the conductor affect resistance within the conductor
Resistance is directly proportional to the length of the conductor as it the current has longer to travel
The cross sectional area is affects the conductors resistance by…
Depending on how thick it is, if it’s thin then more resistance but if it’s thick then less resistance as more room for electrons to flow
How does temperature affect resistance in a conductor?
If it heats up the atoms vibrate more slowing down the electron flow as they get in the way but if it’s cool then electrons can flow smoothly
What type of resistance would insulators be looking at
Very High resistance
What does the insulators resistance depend on?
Thickness of the insulator and material of the insulator
Ohms law is…
Shows the relationship between voltage resistance and current
How to find voltage?
Current X voltage
How to find current?
Voltage \ resistance
How to find resistance?
Voltage / current
Three types of circuits
Series
Parallel
Series parallel
What is a series circuit?
A simple loop from a source with services in SERIES back to the source
Example of series
Christmas lights, if one light goes out they all go out as the electricity can’t get past that trip in the line
How to calculate resistance in a series?
Add up all total resistances of all services
What is a parallel circuit?
Where components are numbered side by side and everything is controlled separately
To figure out resistance in a parallel circuit you must?
Turn the resistance into fractions,
Find the common denominator and then add the fractions up
Flip the result and turn into a whole number
What is unique about a parallel circuit?
The voltage stays the same across the whole circuit
What is a series parallel circuit?
Where a series connects to a parallel circuit
