What is the rule for adding resistors in parallel
1/total r = 1/r1 +1/r2 ….
What is the rule for adding resistors in series
Rt = r1 + r2 + r3 ….
What is power
The energy transferred over time
Rate of energy transfer
What are the power equations
P = VI
E =VIt
What’s the rules for series
Current is the same everywhere in the circuit
The battery p.d is shared across all elements in the circuit therefore the total sum of the voltages is equal to the supply pd
What are the rules in a parallel circuit
The sum of the currents in each branch is equal to the total current
The pd across each branch is the same
When battery cells are joined in series
The total voltage across the cells is equal to the sum of individual cells
VT = V1 +V2 …
When identical cells are joined in parallel
The total voltage is equal to the voltage of one cell this is because the current is split equally between branches therefore the overall potential difference is the same as if the total voltage is flowing through it
In DC circuits charge and energy is
Always conserved
What is kirchoffs first law
The total current flowing into a junction is equal to the current flowing out of that junction
This shows that no charge is lost at any point in the circuit
What is kirchoffs second law
The sum of all voltages in a series circuit is equal to the battery voltage
This shows that no energy is lost at any point in a circuit
