Electricity Flashcards
What is charging by friction?
When 2 insulating materials are rubbed against each other the electrons rub off one and onto the other, depending upon the material. One becomes positively charged and the other negative
How is current found
Current (A - amperes) = Charge (C - coulombs) / time (s)
I = Q/t
What are the symbols for a fixed resistor, a variable resistor, fuse and a diode?
Fixed: Rectangle with line behind
Variable: Rectangle with line behind and diagonal arrow across
Fuse: Rectangle with line in front
Diode: Fast forward button in a circle, with line in front
Where are ammeters and voltmeters (potential difference) placed with the component
A: In series
V: Parallel
What is Ohm’s law
Current is directly proportional to potential difference
What are graphs like for a filament bulb and a diode
F: Curve
D: High resistance so high current, low pd
Difference between a series and a parallel circuit
Series circuits won’t function if there is a break in the circuit. No choice of route.
Parallel circuits will only stop functioning in a certain part if there is a break because there are different choice of route. More useful in life
The bigger the resistance the smaller the current
The bigger the resistance the bigger the pd
How can current through a component in a parallel circuit be calculated
Current (A) = Potential difference (V) / Resistance (ohms)
I = V/R
Name the coloured wire that attaches to which pin
Blue - Neutral
Green/yellow - Earth
Brown - Live
What is earthing
A metal must be earthed to ensure an electrical shock doesn’t happen. In a metal case, it must be earthed so it doesn’t become live and electrocute you.
What is a fuse
Fitted in series with the live wire and if the current is too large it melts and cuts off the live wire from the appliance. Higher than the normal current otherwise it would just blow all the time.
Name 2 different types of fuse that do roughly the same job
Circuit breaker - Electromagnet that opens and cuts the supply if it’s too large
RCCB - Cuts off the live wire also, better because it’s quicker and it doesn’t need replacing but more expensive
How else can power be calculated
Current x potential difference
How can energy be calculated using charge
Charge x potential difference
What is direct and alternating current
Dc: Batteries, the current passes round the circuit in one direction
Ac: The current from the mains supply passes in one direction then reverses and passes in the other direction
