Electrcity Flashcards
current
Flow of electrical charge around a circuit
The unit of a current is the ampere(A,amp)
Series circuit facts
current is never used up and is the same all around
Parallel Circuit
There is more than one branch and the electrical current spits up here but at the end it always adds up to the total current leaving the cell
What is potential difference(voltage)
1v=1 joule of energy is transferred for each coulomb of charge that is moving through the circuit
How to measure potential difference
Voltmeter apply it opposite the cell or lamp or whatever
Potential difference in parallel circuits
For components connected in parallel. Potential difference is the same between components
Potential difference in series circuit
potential difference is split between components
What is electrical charge
Measured in coulombs
A current of 1 amp=1 coulomb of charge flowing/s
Formula for chargeflow
Q=I x t
charge flow= current x time
Formula for energy transferred
E=Q x V
energy transferred (j)= charge flow x volts
Formula for resistance
R=V/I
ohms=volts/amps
What is resistance
Resistance is opposition to the flow of current. A high resistance means it is harder for current to flow through. A low resistance means current will flow through more easily. Resistance is measured in Ohms (Ω).
Fact about proportionate
Current through a resistor is directly proportionate to the potential difference
resistance will only stay constant if the temperature is constant
What is a resistor
A resistor restricts or limits the flow of electrical current
Resistors in series
Add up together
Resistor in parallel
total resistance of two resistors is less than the resistor of the smallest individual resistor
Resistance for LDR at night
Very high
Formula for energy transferred
e=pxt energy= power x time
Formula for power (2)
p= V x I Power= Volts x Current
Formula for power (3)
p=i^2xr Power= current^2 x Resistance
DC( direct current)
Current from a cell is a dc.
AC (alternating current)
goes both ways around a circuit has 50hz and 230 volts from mains
Benefit of AC
Very easy to use a transformer to increase or decrease the Potential difference
Formula for Frequency
Hz= time/time interval
Mains electricity
Alternating current 50Hz 230V
Uses three core cable made from copper but coating from plastic
Brown wire
Live. carries the alternating potential difference from the supply (230)
Connected to a fuse
Exremely dangerous to touch
Blue wire
Neutral. completes the circuit p.d. = 0v compared to the live wire
Green/yellow wire
Earth. safety wire to stop the appliance from becoming live
What would happen if you touch a live wire
a current would flow through the person into the earth and they’d be electrocuted
