Py 212 Test 2

Front 1

Insulator (Dielectric)

Back 1

Material put in a capacitor that increases storage

Front 2

Objects in Series

Back 2

There is no junction between them

Front 3

Objects in Parallel

Back 3

Their ends are directly connected

Front 4

κ (kappa)

Back 4

dielectric constant

Front 5

Capacitors in Series
Have same ____
MOE q123 = ___
Equation

Back 5

1) All have same charge
2) MOE: q123 = q1 = q2 = q3
3) Equation: 1 / Ceq

Front 6

Kirchoff's Loop Rule

Back 6

The sum of potential changes around a closed loop = 0.
*Conservation of ENERGY
Σ ΔV = 0

Front 7

Capacitors in Parallel
Have same ____
MOE q123 = ___
Equation

Back 7

1) All have same potential difference.
2) q123 = q1 + q2 + q3
3) Equation: C eq = C1 + C2

Front 8

Volt (unit)

Back 8

Joule / Coulomb
N*m / C
Watt / Amp

Front 9

Capacitance

Back 9

C = q / ΔV

Front 10

U (energy, charge stored)

Back 10

U = (1/2) * q * ΔV
= (1/2) * c * ΔV^2
= (1/2) * q^2 / C

in Joules

Front 11

Current (I)

Back 11

I == Δq / Δt
= coulomb / sec

Units in Amperes
Current in direction opposite electron flow

Front 12

Drift velocity

Back 12

Very slow - 5e-4 m/s

"Monkeys drift down the mountain"

Front 13

Current (full formula)

Back 13

I = Δq / Δt
= n*e*(v_d)*A

n is number of charge carriers/unit vol
v_d is drift velocity

Front 14

Ohm's Law

Back 14

ΔV = I*R ("suggestion" that R is constant)

Resistance in Ohms
Current Coulomb / sec

Front 15

Resistance
(Ohm's law and full def)

Back 15

R = ΔV / I
= ρ * (l/A)

where ρ is resistivity of material

Front 16

Power

Back 16

Rate work is done
P = W / Δt
= (I^2)*R
= I*ΔV

Front 17

Energy in circuit
Battery
Capacitor
Resistor

Back 17

Battery *provides* energy
Capacitor *stores* energy
Resistor *uses* enerrgy

Front 18

Resistors in Series
Have same ____
MOE q123 = ___
Equation

Back 18

1) All have same current
2) MOE: I123 = I1 = I2 = I3
3) Equation: R123 = R1 + R2 + R3

Front 19

Kirchoff's Point (Junction) Rule

Back 19

Current in = Current out
I1 = I2 + I3 (at junction)

Conservation of charge

Front 20

Resistors in Parallel
Have same ____
MOE q123 = ___
Equation

Back 20

1) All have same voltage
2) MOE: I123 = I1 + I2 + I3
3) Equation: 1/R123 = 1/R1 + 1/R2

Front 21

Capacitance of no capacitor

Back 21

Equal to 1/infinite = 0

Front 22

Capacitors
3 things to find

Back 22

1) q Charge
2) ΔV Voltage
3) C Energy stored

Front 23

Resistors
3 things to find

Back 23

1) I Current
2) ΔV Voltage
3) P Energy used

Front 24

Charging a Capacitor
When charging?
Current does what?

Back 24

Charges when switch is closed
Current stops when fully charged

Front 25

q(t)
Charging Capacitor

Back 25

q(t) = εC [ 1 - e^(-t/τ) ]

where τ = R*C (seconds)
the time constant