Hi everyone, just figured that I'd post an accumulation of what I've been studying for the test tomorrow morning. It goes in video order because that's the order that I learned the material in. If something is too vague, I reccomed looking at the video for elaboration
- Current and Current Density
- Resistors and Resistance
- Voltmeters and Ammeters
- Ideal and Real Batteries
- RC Circuits: Steady State
- RC Circuits: Transient Analysis (Charging)
Current and Current Density:
Current measured in Amps, or charge per sec.
An electric field is applied to a conductor and a small field is created that opposes it
Avg. Velocity of electrons in that field= drift velocity (Vd)
Vol= Bh = Vd * change in time * Area
# electrons = Volume * volume density(AKA "N")= N *change in time* Vd * Area
I= N*q*Vd *A
Current density = J* N*q*Vd
I= integral (J * dA)
Resistance ("Howdy, Y'all!" made my day in that vid, btw)
p = row =resistivity
E=energy=V/L = p (I/A) = pJ
Series: Req= R1 +R2...
Parallel: 1/Req= 1/R1 +1/R2....
Kirchhoff's Current Law= sum all current entering = sum all current exiting (conserv. charge)
Kirchhoff's Voltage Law= sum of all potential drops in a closed loop of a circuit = 0 (conserv. energy)
Voltmeters and Ammeters:
Voltmeters: measures v between two points, high resistance, connected in parallel
Ammeters: measures current, low resistance, connected in series
Ideal and Real Batteries:
Ideal: no internal resistance
V battery = Emf = change in V
Real: has internal resistance
V battery = change in V = IR = Emf- (I)®, where r = internal resistance
W= change in Q * Emf
P= W/change in time = (change in Q)(Emf)/(change in time)
P resistor (works for both external and internal) = I2R
RC Steady State:
series: 1/Ceq= 1/C1 + 1/C2 ...
Parallel: Ceq = C1+C2...
U=1/2 C V2
Time constant Tao=RC, occurs when quantity is 63% of its final value. 5 Tao= 99% final value (practically final value)
Note: an uncharged capacitor acts like a wire, a charged capacitor acts like a gap in the circuit (AKA no current)
...Okay, bed time. Good luck tomorrow, everyone!