ELECTRICITY Flashcards
Potential difference equation
V = W/Q
Work done equation
E = IVt
E.M.F equation
E.M.F = ε/Q
What is an ohmic conductor
When current is proportional to voltage
What effect does increasing the temperature have on a thermistors resistance?
Decreases resistance because the thermistor has an increases energy state, some electrons will move from the valence band into the conduction band and begin to act as charge carriers - lowering resistance
What effect does increasing the temperature have on an filament bulbs resistance?
Resistance increases.
The positive ions vibrate more when temperature increases. This means the charge carriers are much more likely to collide and therefore cannot pass through the material as easily.
What is resistivity
A measure of the amount of resistance per unit length and cross sectional area for a material
Voltage in series and parallel circuits
series - split evenly between components
parallel - constant across components
current in series and parallel
series - constant
parallel - splits
All equations for power
- IV
- (I^2)R
- V^2/R
define E.M.F
Energy stored per unit charge
What is super conductivity?
Resistivity reduces to zero at a critical temperature.
Name 3 uses of super conductors.
Large power transmission
Super conductors
MRI scanners
What is the difference between electrical power and electrical energy?
Power is the rate of change of work.
Energy is capacity to do work
Rearrange the E.M.F equation in the form y=mx+c
V = -rI + ε
