DC Circuits Flashcards
Current in series
Current stays the same at any point but and changes to the voltage or resistance causes change in current
Current in parallel
Current splits at a junction, if the resistance is equal on each side then the current splits equally. However, if the resistance is different at both ends of the junction then the majority of the current takes the path of least resistance.
Kirchoffs first law
Conservation of charge- At a junction, the sum of the currents entering = the sum of the currents leaving
Voltage in series
The voltage splits across components, if not equal resistance then the most resistance needs the most voltage
Voltage in parallel
The voltage stays the same in each loop
Kirchoffs second law
Conservation of energy- In any closed loop in a circuit, the sum of the emf’s is equal to the sum of the pd’s around the loop.
Thermistor- Low Temp
When the temp is low the voltage at the variable resistor is high due to high resistance , this means the fixed resistor has a low voltage.
Thermistor- High Temp
When the temp is high the voltage at the variable resistor is low due to low resistance meaning the fixed resistor has a high voltage
Light dependant resistor (LDR)- Low light
When at low light levels the LDR has high resistance and high voltage therefore the fixed resistor has a low voltage
Light dependant resistor (LDR)- High light
When at high light levels the LDR has a low resistance therefore a low voltage meaning the fixed resistor has a high voltage across it.
Units for
PD-
Resistance-
Power-
Current-
JC-1
VA-1
Js-1
Cs-1
Explain internal resistance equation
V=E-Ir
V=pd across resistor
E= emf from cell
I= current
r=internal resistance
What is the difference between conventional current and electron flow
Electron flow is said that electrons flow from the negative to positive and conventional current is when the current flows from positive to the negative.
