S5 - Physics Unit 3 Flashcards
What uses d.c current mostly?
Battery powered objects
What is the E.M.F of a circuit?
The open circuit voltage
What is the t.p.d of a circuit?
The closed circuit voltage
How do we write ‘lost volts’ in an equation?
Ir
(current and resistance)
What does a capacitor do?
Stores charge
What is the voltage in a capacitor when it is fully charged
Equals the supply voltage
What is capacitance measured in?
Farads (F)
What does the area under a charge-voltage graph equate to?
Energy
What are valence bands?
Where electrons are stored in an atom
What is the outer most valence band, that isn’t full, of an atom called?
The conduction band
What happens when temperature is increased to electrons?
They gain energy and break free of the valence band, allowing them to move into the conduction band
What is a depletion layer?
A layer in which no electrons or ‘holes’ can move past
What happens in forward bias of a p-n junction?
When enough voltage is applied, electrons and ‘holes’ can over come the depletion layer as a result of the electrons moving from n-type towards the positive side of the battery over the depletion layer while ‘holes’ move towards the negative side, allowing a charge to flow
What happens in reverse bias of a p-n junction?
Electrons and ‘holes’ are attracted to each other and therefore repel each other, making the depletion layer bigger
What is meant by ‘rms’ voltage?
The root mean square voltage
