exam 2 Flashcards

:) (40 cards)

1
Q

Capictors in series

A

1/Ceff=ε/Q=1/C1+1/C2+1/C3…

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2
Q

How to increase capacitance?

A

Increase the area of the plate
Use diaelectrics (insulator with polarized molecules in between so that E field in between plates becomes weaker)

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3
Q

Energy Storage in a capacitor

A

U= QV/2

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4
Q

Capcitance general formula

A

C=Q/V where Q is charge moved and V is volatage (epsilon)

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5
Q

Capactitors strategies

A

label everything really really well and stay consistent
Identify capacitors in series and parallel and combine

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6
Q

Ohms law for voltage

A

V=IR

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7
Q

Time constant RC cricuit

A

Tau=RC

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8
Q

Magnetic F on a moving charge
Formula and direction

A

F=qV×B
The F is perpendicular to both the velocity of the charge and the magnetic field

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9
Q

Magnetic flux

A

∫∫B*dA=0

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10
Q

Radius for circular motion of particle

A

r= mV/qb

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11
Q

Period for circular motion of particle

A

T=2pim/qB

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12
Q

Frequency

A

1/T=qB/2pim

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13
Q

Capacitors in parallel

A

Ceff=Q/ε=C1+C2+C3…

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14
Q

Resistors in series

A

Rseries =R1+R2+R3… (opp of capacitance in series)

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15
Q

Resistors in parallel

A

1/Rparallel=1/R1+1/R2+1/R3…
RESISTORS IN PARALLEL HAVE THE SAME VOLTAGE

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16
Q

Finding voltage RC circuit

A

FIRST-consider initial conditions @t=0
THEN what happens when t->infinity
use loop law
consider = voltage drop given by Ohm’s law

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17
Q

Resistivity

A

R= pL/A
Resistivity depends on the material, the length (the longer the object the larger the resistance)

18
Q

Electric power (P)

dissapted through resistor

A

P=IV
P=I^2R
since V=IR

19
Q

Current def (I)

20
Q

Current understanding

A

I=nqvdA
where n is the number of charge carriers, q is the charge, v is the drift velocity, and dA is cross sectional area

21
Q

Magnetic force on a current

A

F(vector)=I L*B (take cross product of vectors L and B)

22
Q

Hall voltage

23
Q

Lorentz force

24
Q

Magnitude of velocity for particle under influence of both Fe and Fm

25
Parallel Resistors have the same...
Voltage (V)
26
Resistors in series have the same...
Current (I)
27
If V0=E/B and if the three vectors are pointing perpendicular to each other in the appropriate directions
then the charged particle will travel in a straight line without deflection
28
Voltage on a current over time in an RC circuit
Vc (t) =esplison (1-e^(-t/tau))
29
Loop law RC charging
Vc+Vr=epsilon
30
Loop law Rc discharging
Vc+Vr=0
31
V of resistor over time because of the loop law
start with loop law Vr+Vc=epsilon Vr=epsilon-Vc Start with epsilon and decreases exponentially
32
Flow of current in a RC current
Battery moves (+) charges from one side of capacitor to other side of the capacitor, travels through resistor on the way there
33
Elecrtic potential
U=Vq think like potential energy -> can all convert to kinetic energy
34
Charge change when discharging a capcacitor
Q(t)= Q0 (e−t/ τ)
35
Energy stored on a capacitor
U=Q^2/2C
36
Capacitors in parallel have the same
Voltage (V)
37
Capacitors in series have the same
charge (Q)
38
Capacitance of parallel plate capacitors
C= epsilon A/d
39
Energy density of an electric field
nu=1/2 epsilon E^2
40
Current density
=I/A