Electricity Flashcards
Critical temperature of a superconductor
Temperature at and below which the resistance is 0
Electromotive force (emf)
The amount of electrical energy per unit charge produced inside a source of electrical energy
E/Q
Energy
Ability to do work
Internal resistance (Ir)
Resistance inside a source of electrical energy; the loss of PD per unit current in the source when current passes through it
How does light intensive it affect LDR
Resistance decreases with increase in light intensity
Negative temperature coefficient
Resistance of a semi conductor decreases when it’s temperature increases
Why do semiconductors gave a negative temperature coefficient
Number of charge carriers increases as there is extra energy
So more free electrons to carry current
Ohms law
The pd across a metallic conductor is proportional to the current. It’s resistance is constant
Positive temperature coefficient
The resistance of a metal increases when it’s temperature increases
Why do metals have a positive temperature coefficient?
Increases the resistance because it gets warm and ions in the metal vibrate more
Metal ions collide more with the flow of electrons
Harder for current to flow through
Potential difference
Energy transferred per unit charge between two points when charge moves from one point to another
[JC^-1]
Potential divider
Two or more resistors connected in series in order to obtain a variable voltage
Power
Rate of transfer of energy
Current
Flow of charge per second
[Cs^-1]
Resistance
Measure of how difficult it is for current to flow in an object
