Analogue Electronics Flashcards
A parralel-plate capacitor consists of…?
Two conductive plates seperated by a dielectric layer
Does net charge cross a capictor?
No
What do capacitors try to do to the voltage across the plate?
Try to keep it constant
What does the cicrcuit symbol for capacitance look like?
What does a capacitor represent in terms of fluid flow analogy?
A capacitor represents a reservoir with an elastic membrane separating the intlet and outlet
What is the equation for charge?
q=Cv
What is the relationship between current and voltage?
v(t) = ?
This is the graph of voltage vs time, what would charge vs time and current vs time look like?
Voltage is the intergral of…?
Current
w(t) = ?
w(t) = ½vq = q2 /2c =
If this is v-t, what would i-t, p-t and w-t look like?
How do you work out the total capacitance for capacitors in parralel?
Add them up (suppose to be C3 - it’s in the book)
How do you work out the total capacitance for capacitors in series?
1/C
What’s the equation for the capacitance of a parallel plate capacitor?
What does an inductor look like?
Basic equations for inductor/conductance?
How do you work out inductors in series and in parallel?
- In series
- You add them
- In parallel
- You do 1/L
It’s exactly the same as resistors!
Capacitors don’t like…?
Instantaneous changes in voltage
Inductors don’t like…?
Instantaneous changes in current
V1(t) = ?
V1(t) = Vs(1-e-t/2)
2 equations
L/R and
3 equations
And V = IR & V = CR
For infinite steady state; (what type of circuit)
- Inductors = ?
- Capcitors = ?
- Voltage across the capacitor = ?
- Inductors = closed/short circuit
- Capacitors = Open circuit
- 0V
How is the homogeneous equation obtained?
By setting the forcing function to zero
- What is the forcing function?
- And if we have a circuit without sources, what is the forcing function?
- And what is the forcing function for dc sources?
- A function of only resistances and the inductance (or capacitance)
- 0
- Constant
How is the natural response obtained?
By solving the homogeneous equation
VRMS = ?
cos2(z) = ?
(1 + cos(2z))/2
How do you solve phasers?
- Determine the phasors
- Change the phasors to cartesian (rectangular) form
- Add Re and Im part
- Express sum as phason (polar form)
- Express as a time (cos) function
- Leading is…
- Lagging is…
- Leading is infront
- Lagging is behind
- R = ?
- Z (____ ____) = ? = ?
- R = V/I
- Z (Complex impeadance) = V/I = jWL
ZL = ?
Current lags
Zc = ?
Voltage lags
w (omega) = ? (two equations)
= 2π/T
f = ?
f = 1/T
v(t) = ? (cos one)
sin(z) = ? (for degrees and radions)
Vrms = ?
Pavg = ?
Pavg = I2rmsR
V = ? so ?(diff) = ? so eventually = ?
What does V1 lead V2 by?
60°
For a pure resistance, current and voltage are…?
In phase
What do power triangles for
- Inductive loads
- Capacitive loads
Look like?
What does the Thévenin equivalent for an ac circuit consist of?
A phasor voltage source, Vt, in series with a complex impedance Z
What does a Norton equivalent circuit consist of?
A phasor current source in in parallel with the complex impedance Zt
Averge power over a period P =?
Irms = ?
What would a balanced 3 phase voltage source look like?
P = ? (resistance equations)
P = I2R and P = V2/R
The term cosØ is called…?
Power factor or power angle
Reactive power Q = ?
Q = VrmsIrmssin(Ø)
Vm = ?
w(omega) = ?
Ø = ?
Vm = Maximum value
w(omega) = Angular frequency (Rad/s)
Ø = Phase angle
Power traingle for inductive loads? (ø positive)
Power triangle for Capacitive load? (ø negative)
Triangle for z?
The impeadance z = ? (additional power relationships)
In this equation
P = V2Rrms/R
VRrms is the…?
VRrms is the rms voltage across the resistance
In this equation
Q = V2Xrms/X
VXrms is the…?
VXrms is the rms voltage across the reactance
X is ____ for inductance
X is negative for ____
X is positive for inductance
X is negative for conductance
In Thévenin Equivalent Circuits,
Vt = ?
Zt = ?
Vt = Voc
Zt = Voc/Isc = Vt/Isc
If the circuit has ____ and ____ sources,
Rth (Thévenin) = ?
If the circuit has independent and dependent sources,
Rth (Thévenin) = RN = Voc/Isc
Isc = ?
Isc =
Ohm’s Law = V/R
This is a Thévenin equivalent circuit, what would a Norton equivalent circuit look like?
If the circuit has only ____ sources,
Vth = ?
IN = ?
Rth = Rn = ? ⇒ ___ _ ______ __ ___ _______
If you had a voltage source you work out the…?
If you add a current source you work out the…?
If the circuit has only dependant sources,
Vth = 0
IN = 0
Rth = Rn = ? ⇒ add a source to the circuit
If you had a voltage source you work out the…current
If you add a current source you work out the…voltage
There are 3 different scenarios to find Rn (R Norton) and RTh (R Thévenin), how do you do it when there’s…
- Only independent sources
- Only dependent sources
- Both dependent and independent sources
There are 3 different scenarios to find Rn (R Norton) and RTh (R Thévenin), how do you do it when there’s…
- Only independent sources
* Kill all the sources and find Req - Only dependent sources
- Add a source
- If it’s a current source you find voltage using Ohm’s law,
- If it’s a voltage source you find current using Ohm’s law
- Both dependent and independent sources
* Voc/Isc
Vth = ?
IN = ?
Vth = Voc
IN = Isc
What would the Thévenin equivlent circuit look like?
What would the Norton equivalent circuit look like?
What is the superposition principle?
The superposition principle states that the total response is the sum of the responses to each of the independent sources acting individually
The thèvenin voltage is equal to the…?
…open circuit voltage
Vt = Voc
When sources are zeroed, current sources become ____ ____ and voltage sources become ____ _____
When sources are zeroed, current sources become open circuits and voltage sources become short circuits
Pavg = ? = ?
Pavg = V2rms/R = I2rmsR
Total energy absorbed, w = ?
w = ∫ p(t) dt
What resistance value should be chosen for RL to achieve maximum power transfer from the circuit to the load?
The Thévenin equivalent resistor
