Chapter 10: DC Circuits Flashcards
(25 cards)
Function of electrical component: switch
Turn the circuit on (closed), or off (open).
Function of electrical component: diode
A diode allows current to flow in one direction only.
Function of electrical component: fixed resistor
A resistor limits the flow of current. A fixed resistor has a resistance it cannot change.
Function of electrical component: variable resistor
A resistor with a slider that can be used to change its resistance. Used often in dimmer switches and volume controls.
Function of electrical component: thermistor
The resistance of a thermistor depends on its temperature. As the temperature increases, its resistance decreases and vice versa.
Function of electrical component: light dependant resistor
The resistance of an LDR depends on the light intensity. As the light intensity increases, its resistance decreases and vice versa.
Function of electrical component: light emitting diode
This is equivalent to a diode and emits light when a current passes through it. These r used for aviation lighting and displays (TV’s, road signs).
Function of electrical component: ammeter
Used to measure the current in a circuit. Connected in series with other component.
Function of electrical component: voltmeter
Used to measure potential difference of an electrical component. Connected in parallel with component.
EMF defintion
The EMF is the amount of energy transferred per coulomb of charge when charge passes through a power supply. It is a measure of energy transferred into the circuit by the power source.
What is internal resistance?
Loss of voltage/energy in a power supply.
EMF formula
E = IR + Ir = I(R+r)
What is IR?
terminal PD
What is Ir
Lost volts
State Kirchhoffs first law
The sum of current entering a junction is always equal to the sum of the currents exiting a junction.
What is a junction?
A point where at least 3 circuit paths meet
What is a branch?
Is a path connecting 2 junctions.
State Kirchhoffs second law
The total emf in a closed circuit is equal to the sum of the potential differences across the components.
Kirchhoffs second law is a consequence of?
Conservation of energy
Kirchhoffs first law is a consequence of?
Conservation of charge
Resistors in series formula
R = R1 + R2 + R3 + …
Resistors in parallel formula
1/R = 1/R(1) + 1/R(2) + 1/R(3) + …
State 3 main purposes of potential dividers
Provide a variable potential difference
To enable specific potential differences to be chosen
To split the potential difference of a power source between two or more components.
Potential dividers formula
V(out) = (R(2)/(R(1)+R(2))) * V(in)
