Chapter 6: Circuits

Question 1

current (I)

Answer 1

the amount of charge passing through the conductor per unit time

Q / delta T

(the flow of positive charge

flows from a positive terminal to negative terminal

Question 2

metallic conductivity

Answer 2

current flows through metals atoms

Question 3

electrolytic conductivity

Answer 3

current flows through ionic solution

Question 4

conductivity

Answer 4

a measure of permissiveness to current flow; measure in siemens

reciprical to resistance

Question 5

SI unit for conductance

Answer 5

siemens

Question 6

current units

Answer 6

coulombs / sec = ampere (A)

1 A = 1 C/s

Question 7

direct current

Answer 7

current flows in one continuous direction

Question 8

alternating current

Answer 8

current which periodically reverses direction and changes its magnitude continuously with time

Question 9

voltage (potential difference)

Question 10

electromotive force (emf)

Answer 10

the potential difference of the voltage source for a circuit, usually a battery

given in volts

Question 11

voltage units

Answer 11

1 V = 1 J/C

Question 12

Kirchhoff’s Junction Rule

Question 13

Kirchhoff’s Loop Rule (?)

Answer 13

V source = V drop

Question 14

resistance

Answer 14

the opposition within any material to the moment and flow of charge

a measure of the opposition to current flow in an electrical circuit

Question 15

conductors

Answer 15

materials that offer almost no resistance to current flow

Question 16

insulators

Answer 16

materials that offer very high resistance to current flow

Question 17

resistors

Answer 17

conductive materials that offer amounts of resistance between conductors and insulators

more conductive than insulators, less conductive than conductors

regulate current flow

Question 18

characteristics that affect resistance of a resistor

Answer 18

resistivity, length, cross-sectional area, and temperature

Question 19

resistance equation

Answer 19

R = ρL/A

ρ = resistivity, L = length, A = cross-sectional area

Question 20

resistivity (ρ)

Answer 20

the number that characterizers the intrinsic resistance to current flow in a material (constant for a given material and temperature)

Question 21

resistance and length

Answer 21

positive linear relationship

doubled length = doubled resistance

Question 22

cross-sectional area

Answer 22

inverse linear relationship

cross-sectional area doubled = resistance halved

Question 23

conduction pathways

Answer 23

a route for current to take through a resistor

a wider resistor has more conduction pathways within

Question 24

temperature and resistance

Answer 24

most conductors have higher resistance at higher temperatures

hot wire = more resistance

Question 25

Ohm's Law equation

Answer 25

V = IR V = voltage drog I = current R = magnitude of resistance

Question 26

current flows from ____ to \_\_\_\_

Answer 26

current flows from positively charge, high potential to negatively charged, low potential

Question 27

secondary batteries

Answer 27

can be recharged out outside source provides voltage to the positive end of the battery

Question 28

Power of resistor

Answer 28

rate at which the resistor dissipates energy from the circuit (to another form of energy, ex. heat or light) P = IV = I^2R = V^2/R

Question 29

equivalent / resultant resistances (series)

Answer 29

the sum of the individual resistances

Question 30

equivalent resistance (resistors in parallel)

Answer 30

RP will always decrease as more resistors are added

Question 31

capacitor

Answer 31

an electronic component that stores electrostatic energy in an electric field a device that stores electrical energy (charge?) by putting positive charges on one plate and negative charges on another plate, creating an electric field uses 2 metal plates separated by an insulator and stores electrical charge by pumping electrons from one side to another

Question 32

capacitor type covered on the MCAT

Answer 32

parallel plate capacitor

Question 33

capacitance equation

Answer 33

C = Q/V Q = the magnitude of the charge stores on one plate V = the voltage across the capacitor

Question 34

SI unit for capacitance

Answer 34

farad 1 F = 1 coulomb / volt

Question 35

capacitance of a parallel plate capacitor

Answer 35

Question 36

uniform electric field equation

Answer 36

E = V/d

Question 37

capacitor function

Answer 37

to store an amount of energy in the form of charge separation at a particular voltage

Question 38

potential energy store in a capacitor

Answer 38

U = ½ CV^2

Question 39

dielectric material

Answer 39

synonymous with insulator

Question 40

dielectric materials ____ (increase/decrease) the capacitance of the capacitor

Answer 40

dielectric materials **increase** the capacitance of the capacitor

Question 41

dielectric constant (K)

Answer 41

a measure of a given materials insulating ability a vacuum has a dielectric constant of 1

Question 42

capacitance due to a dielectric material

Answer 42

C' = kC C' = the new capacitance with the dielectric present C = the original capacitance

Question 43

equivalent capacitance _______ (increases/decreases) as more capacitors are added in series

Answer 43

decreases

Question 44

resultant capacitance of capacitors in parallel…

Answer 44

is equal to the sum of the individual capacitances

Question 45

meters

Answer 45

the devices used to measure circuit quantities (current, voltage, resistance, capacitance) in the real world

Question 46

ammeters

Answer 46

used to measure the **current** at some point within a circuit ("am" → amp) require a circuit to be active

Question 47

voltmeters

Answer 47

creates an alternate pathway for the current in order to measure the voltage drop from the 2 points where it connects to the original circuit have very high resistance so not many electrons take this alternate path require a circuit to be active

Question 48

ohmmeters

Answer 48

does NOT require a circuit to be active the meter measures the current, and then uses the known voltage and Ohm's law to determine resistance