Mt Flashcards
What is the structure of an atom?
A nucleus in the centre with positive protons and negative neutrons inside.
Negative electrons orbiting in energy shells/levels around the nucleus.
What do like and unlike changes do?
Like charges repeal.
Unlike changes attract.
What is electrical current?
Rate of flow of charge.
What is potential difference?
Difference in the amount of energy that charge carriers have between 2 points in a circuit.
Why does p.d cause current to flow in a wire?
The negative electrons are attracted to the positive terminal and are repelled from the negative terminal.
What is resistance?
The measure of impedance of electrical current, the greater the resistance the lower the current.
How are current and p.d shared in series?
Current is same everywhere.
p.d is split between components.
How are current and p.d shared in parallel?
Current is split between loops.
p.d is the same between loops.
What is the purpose of a diode?
Electrical 1 way streets, letting current flow in positive direction.
What is the purpose of a thermistor?
Thermal resistor, resistance decreases with increases temperature.
What is the purpose of a LDR?
Resistance decreases with increased light.
Which is used for the mains, AC or DC?
AC, 230/240v and 50hz.
What is AC and DC?
AC = alternating current.
DC = direct current.
What are the wires in plug?
brown = live (right)
blue = neutral (left)
green/yellow = earth (top)
Why do we have step up transformers before pylons in the national grid?
High current causes heating in wires which means loss of energy.
Increase p.d, decrease current, send electricity slowly through wires on the national grid.
P.d equation = ?
Current equation = ?
Resistance equation = ?
What are series and parallel circuits?
What are are I/V graphs for an : ohmic conductor, diode and a bulb.
What are the AC and DC graphs?
What are the 4 equations for power?
