circuits

Question 1

current

Answer 1

I = Q/ deltaT

measured in ampere 1A = 1 C/s

Question 2

Definition of resistance

resistivity

Answer 2

R = (rho)L / A
L = length
A = cross sectional area
measured in ohm-meter

Question 3

Ohm’s Law

Answer 3

V=IR

Question 4

emf: electromotive force

Answer 4

the voltage with no current running through

Question 5

Voltage accounting for internal resistance

or voltage & EMF relation

Answer 5

V = Ecell - (I)(Rint) 
Ecell= emf 
Rint = internal res

Question 6

Definition of power

Answer 6

work per unit time
P = work/time = W/t = delta E / t

delta E = change in energy (KE?)

Question 7

Electric power
or energy dissipated by resistor
or power of resistor

Answer 7

P = IV = (I^2)R = V^2/R

in regards to time:
P = E/delta T
definition of power

Question 8

Resistors in series

Answer 8

Rs = R1 + R2 + R3…

resistance will increase as more resistors added

Question 9

Resistors in parallel

Answer 9

1/Rp = 1/R1 + 1/R2…

resistance will decrease as more resistors added

Question 10

Definition of capacitance

Answer 10

C = Q/V
C = charge/voltage
measured in farad 1F = 1 C/V

Question 11

Capacitance of parallel plates

Answer 11

C = eo (A/d)
A= area of overlap of two plates 
d = distance between 
eo = permittivity of free space

Question 12

On parallel plate capacitor, the separation of charges sets up a uniform electric field that has a magnitude of:

Answer 12

E = V/d

V=

Question 13

energy of charged capacitor

or potential energy in capacitor

Answer 13

U = (1/2)C(V^2) 
C= capicitance I guess
V= voltage I guess

Question 14

Capicitance with dielectric material,

how does it change?

Answer 14

C’ = kC
k = dielectric constant
will increase capacitance …. how?

isolated capacitors ( disconnected): Capacitor increases capicitance by lowering the voltage 
(lower V when Q is constant) 

in circuits: capacitors increase capacitance by increasing charge
(inc Q when V is constant)

Question 15

Capacitors in series

Answer 15

1/Cs = 1/C1 + 1/C2 + 1/C3….

Question 16

Capacitors in parallel

Answer 16

Cp = C1 + C2….

Question 17

Kirchoff

Answer 17

closed loop V = 0 total

Question 18

Conductivity theory

Answer 18

• no electrolytes = no ionization = no conductivity
• optimal [C] of electrolytes = highest mobility and condy
• too many e-lyte = crowding = no mobility or conductivity
• conductivity decreases as temp inc in metals
• conductivity increases as temp inc in semimetal s