Ch. 6: Circuits

Question 1

where is metallic conductivity seen

Answer 1

solid metals and some molten salts

Question 2

where is electrolytic conductivity seen

Answer 2

solutions

Question 3

unit of conductance

Answer 3

siemens (S)

S/m

Question 4

what is conductance the reciprocal of

Answer 4

resistance

Question 5

why are metal atoms good electrical conductors

Answer 5

• easily loose one or more valance electrons

- these electrons then move about in larger collection of metal atoms

Question 6

what does electrolytic conductivity of a solution depend on

Answer 6

the strength/ion concentration of that solution

Question 7

equation for current

Answer 7

I = Q / delta t

current = charge passing through conductor / unit of time

Question 8

unit for current

Answer 8

ampere

A = C/s

Question 9

relationship between current direction and ion flow

Answer 9

current is SAME direction of proton flow (high to low potential)
current is OPPOSITE direction of electron flow (low to high potential)

Question 10

direct current flow pattern

Answer 10

charge flows in one direction

Question 11

alternating current flow pattern

Answer 11

charge flow changes directions periodically

Question 12

Kirchoff’s Junction Rule

Answer 12

I into junction = I leaving junction

Question 13

Kirchoff’s Loop Rule

Answer 13

V source = V drop

Question 14

units of electromotive force (emf)

Answer 14

V = J/C

Question 15

resistance

Answer 15

opposition within any material to the flow of charge

Question 16

equation for resistance

Answer 16

R = [p * L] / A

resistance = [resistivity of material * length of material ] / cross sectional area

Question 17

units of resistivity

Answer 17

p = ohm * meters

Question 18

effect of temperature on resistance

Answer 18

resistance is usually higher at higher temps

Question 19

formula for voltage drop between two points

Answer 19

V = IR

Question 20

equation for actual voltage supplied by a cell

Answer 20

V = E cell - [i * r int]

voltage = emf of the cell - [current through the cell * internal resistance]

Question 21

equation for power of a resistor

Answer 21

P = IV = I^2 * R = V^2 / R

Question 22

total resistance of resistors in series

Answer 22

Rs = R1 + R2 + R3 …

Question 23

total voltage drop for a series of resistors

Answer 23

Vs = V1 + V2 + V3 …

Question 24

total voltage for parallel resistors

Answer 24

Vp = V1 = V2 + V3 …

Question 25

total resistance of resistors in parallel

Answer 25

1/Rp = 1/R1 + 1/R2 + 1/R3

OR

Rp = [R1 * R2] / [R1 + R2]

Question 26

definition of capacitance

Answer 26

ratio of the magnitude of charge stored on one plate to the potential difference (voltage) across the capacitor

Question 27

equation for capacitance (when voltage is applied)

Answer 27

C = Q / V

Question 28

unit of capacitance

Answer 28

farad, F

1 F = 1 C/V

Question 29

equation of capacitance of a capacitor

Answer 29

C = E0 (A/d)

Capacitance = permittivity of free space [area / separation]

Question 30

equation for uniform electric field established between two plates of a capacitor

Answer 30

E = V/d

Question 31

equation for potential energy stored within a capacitor

Answer 31

U = 1/2 CV^2

Question 32

capacitance due to a dielectric material

Answer 32

C’ = kC

Question 33

total capacitance of capacitors in series

Answer 33

1/Cs = 1/C1 + 1/C2 + 1/C3 …

Question 34

total capacitance for capacitors in parallel

Answer 34

Cp = C1 + C2 + C3

Question 35

what do ammeters measure

Answer 35

current

Question 36

how are ammeters inserted

Answer 36

in series

Question 37

what do voltmeters measure

Answer 37

voltage drop

Question 38

how are voltmeters inserted

Answer 38

in parallel

Question 39

what do ohmmeters measure

Answer 39

resistance