Current and Charge
P= V2 / R
Total resistance in series: R1 + R2
Total resistance in parallel: 1/R (total) = 1/R1 + 1/R2
V out = V in x R2 / R1+R2
Energy = power x time
J=kW x 3600 seconds
If question is asking for answer in joules, Multiply the power in watts by the amount of time in seconds. If it is asking for the answer in kWh multiply the power in kW by the time in hours.
N2 / N1 IS EQUAL TO
VS / VP IS EQUAL TO
IP / IS
N1 IS PRIMARY COIL
N2 IS SECONDARY COIL
V IS VOLTAGE
I IS CURRENT
AC AND DC
AC rapidlty switches the direction of flow of electrons (in the UK we have AC at 50Hz)
DC travels only in one direction
use a diode to convert AC to DC
Current in series
In a series no matter where you put the ammeter, the current will always be the same. this is because current is not used up.
Current in parallel
The current in a parallel circuit splits into different branches then combines again before it goes back into the supply. When the current splits, the current in each branch after the split adds up to the same as the current just before the split.
Voltages in series
- The supply voltage is shared between components in a series circuit.
- The sum of the voltages across components in series is equal to the voltage of the supply.
- The voltages across each of the components in series is in the same proportion as their resistances. This means that if two identical components are connected in series, the supply voltage divides equally across them.
Voltage in parallel
The voltage across components in parallel is the same for each component
R= (p x L) / (A)
where R= resistance
L=legnth of wire
A= cross sectional area m2