exam 2

Question 1

Capictors in series

Answer 1

1/Ceff=ε/Q=1/C1+1/C2+1/C3…

Question 2

How to increase capacitance?

Answer 2

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

Question 3

Energy Storage in a capacitor

Answer 3

U= QV/2

Question 4

Capcitance general formula

Answer 4

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

Question 5

Capactitors strategies

Answer 5

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

Question 6

Ohms law for voltage

Answer 6

V=IR

Question 7

Time constant RC cricuit

Answer 7

Tau=RC

Question 8

Magnetic F on a moving charge
Formula and direction

Answer 8

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

Question 9

Magnetic flux

Answer 9

∫∫B*dA=0

Question 10

Radius for circular motion of particle

Answer 10

r= mV/qb

Question 11

Period for circular motion of particle

Answer 11

T=2pim/qB

Question 12

Frequency

Answer 12

1/T=qB/2pim

Question 13

Capacitors in parallel

Answer 13

Ceff=Q/ε=C1+C2+C3…

Question 14

Resistors in series

Answer 14

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

Question 15

Resistors in parallel

Answer 15

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

Question 16

Finding voltage RC circuit

Answer 16

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

Question 17

Resistivity

Answer 17

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

Question 18

Electric power (P)

dissapted through resistor

Answer 18

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

Question 19

Current def (I)

Answer 19

I=dq/dt

Question 20

Current understanding

Answer 20

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

Question 21

Magnetic force on a current

Answer 21

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

Question 22

Hall voltage

Answer 22

VH= vBh

Question 23

Lorentz force

Answer 23

F=qE+qV*B

Question 24

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

Answer 24

V= E/B

Question 25

Parallel Resistors have the same…

Answer 25

Voltage (V)

Question 26

Resistors in series have the same…

Answer 26

Current (I)

Question 27

If V0=E/B and if the three vectors are pointing perpendicular to each other in the appropriate directions

Answer 27

then the charged particle will travel in a straight line without deflection

Question 28

Voltage on a current over time in an RC circuit

Answer 28

Vc (t) =esplison (1-e^(-t/tau))

Question 29

Loop law RC charging

Answer 29

Vc+Vr=epsilon

Question 30

Loop law Rc discharging

Answer 30

Vc+Vr=0

Question 31

V of resistor over time because of the loop law

Answer 31

start with loop law Vr+Vc=epsilon
Vr=epsilon-Vc
Start with epsilon and decreases exponentially

Question 32

Flow of current in a RC current

Answer 32

Battery moves (+) charges from one side of capacitor to other side of the capacitor, travels through resistor on the way there

Question 33

Elecrtic potential

Answer 33

U=Vq
think like potential energy -> can all convert to kinetic energy

Question 34

Charge change when discharging a capcacitor

Answer 34

Q(t)= Q0 (e−t/ τ)

Question 35

Energy stored on a capacitor

Answer 35

U=Q^2/2C

Question 36

Capacitors in parallel have the same

Answer 36

Voltage (V)

Question 37

Capacitors in series have the same

Answer 37

charge (Q)

Question 38

Capacitance of parallel plate capacitors

Answer 38

C= epsilon A/d

Question 39

Energy density of an electric field

Answer 39

nu=1/2 epsilon E^2

Question 40

Current density

Answer 40

=I/A