circuits Flashcards
what happens when resistors are added in parallel
their combined resistance decreases and is, therefore, less than the resistance of the individual components
For example, If two resistors of equal resistance are connected in parallel, then the combined resistance will halve
current in a series vs parallel circuit
- In a series circuit, the current is the same for all components
- In a parallel circuit, the current is split across the different branches (or junction). The total current into a junction must equal the total current out of a junction
- The amount of current in each branch depends on the total resistance of the components within that branch
potential difference in a series vs parallel circuit
- In a series circuit, the e.m.f of the power supply is shared amongst all the components in different amounts, depending on their resistance
- In a parallel circuit, the voltage of all the components in each branch is equal to the e.m.f of the power supply
what is Kirchhoff’s First Law
The sum of the currents entering a junction always equal the sum of the currents out of the junction
def of a junction and branch
- A junction is a point where at least three circuit paths meet
- A branch is a path connecting two junctions
what is Kirchhoff’s Second Law
The total e.m.f. in a closed circuit equals the sum of the potential differences across each component
voltage in a series vs parallel circuit
- In a series circuit, the voltage is split across all components depending on their resistance
The sum of the voltages is equal to the total e.m.f of the power supply - In a parallel circuit, the voltage is the same across each closed loop
The sum of the voltages in each closed circuit loop is equal to the total e.m.f of the power suppl
what are the purposes of potential dividers
To provide a variable potential difference
To enable a specific potential difference to be chosen
To split the potential difference of a power source between two or more components
uses of a thermistor circuit
A thermistor circuit is used in fire alarms, ovens and digital thermometers
Potential divider equation and diagram
potential divider definition
A combination of resistors in series connected across a voltage source
