5. Electricity Flashcards
What is potential difference?
The work done per unit charge
What is the emf?
The sum of emf = the sum of p.d in a complete circuit
What is Ohm’s Law?
The current is directly proportional to Voltage, as long as physical conditions remain constant
How does a thermistor work?
They have a negative temperature coefficient.
As temperature increases, the resistance decreases as the number of charge carriers increase due to the addition of energy
How does an LDR work?
Luminosity increases, the resistance decreases.
Electrons in valence band are excited to the conduction band and introduce more charge carriers, which increase the current
What factors affect resistance.
Temperature increases resistance
Length increases resistance
Area decreases the resistance
What is the equation for resistivity?
R = ρL/A
What are superconductors?
Certain materials have zero resistance when cooled below a transition temperature.
This means no energy is lost as heat
What are the applications of superconductors?
Reduces energy loss as heat for electrical power so more efficient, and can conduct larger electrical currents
Material can expel magnetic fields
