Electricity Flashcards
State the charge and relative mass of protons, neutrons and electrons
Protons = (charge) +1, (relative mass) 1
Neutrons = (charge) 0, (relative mass) 1
Electrons = (charge) -1, (relative mass) 1/2000
Define Conductor
Material that allows the flow of electric current
Define Insulator
Material that doesn’t allow the flow of electric current
What does LDR stand for?
Light Dependent Resistor
Which direction does convectional current go in?
+ to -
Which direction do electrons go?
– to +
State the unit for energy
Joules (J)
State the unit for Power
Watts (W)
(same as joules per second (J/s))
State the formula for power
P = E/T
(Power = Energy used/Time)
AC
Alternating Current
A current which is constantly changing in direction
Name a source of AC
Mains Electricity
50Hz (voltage changes 50 times per second)
230V
DC
Direct Current
A current that is always flowing in one direction
Name of source of DC
Cells or Batteries
Name the 3 wires
Neutral
Live
Earth
What is a neutral wire?
A wire that completes the circuit to the power station
Is kept at 0 volts by the electricity company
Blue
What is a live wire?
A wire that carries the high voltage
Connects the appliance to generators at the power station
Brown
What is an earth wire?
A wire needed to earth appliances with a metal case.
Connects the appliance to the ground outside the building.
This makes it safer to touch the appliance if it developed a fault.
What is a fuse?
A safety device containing a thin metal wire that melts if the current is too high
What is a RCCB?
Residual Current Circuit Breakers
They detect a difference in current between live and neutral wires.
They use electromagnets to break the circuit if the current difference becomes too large.
Current
The flow of electrical charge
Which 2 things are needed for a current to flow through an electrical component?
A potential difference across the component
A complete circuit
What is a voltmeter?
It measures what in what and how is it connected
Connected in parallel
Measure PD in volts
Ammeter
Connected in series
Measure current in amps
State the formula for charge
Q = It
Charge = Current x time
State the formula for energy
E = QV
Energy = Charge x voltage
Give another name for Potential Difference
Voltage
What is a series circuit?
A circuit with only one loop
What is a parallel circuit?
A circuit with two or more loops
What is the rule for current in a series circuit?
It’s the same everywhere
What is the rule for current in a parallel circuit?
It splits up
What is the rule for PD in a series circuit?
It splits up
What is the rule for PD in a parallel circuit?
It’s the same everywhere
What is the rule for resistance in a series circuit?
Add resistances to find the total
What is the rule for resistance in a parallel circuit?
Total resistance is less than the lowest resistor
What are the differences between DC and AC?
DC is always in the same direction and always has the same magnitude.
AC changes direction and changes magnitude.
Do convectional current and electrons go in the same direction?
No
Convectional current goes from + to -
whereas
Electrons go from - to +
