Chapter 6: Circuits Flashcards

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1
Q

current (I)

A

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

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2
Q

metallic conductivity

A

current flows through metals atoms

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3
Q

electrolytic conductivity

A

current flows through ionic solution

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4
Q

conductivity

A

a measure of permissiveness to current flow; measure in siemens

reciprical to resistance

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5
Q

SI unit for conductance

A

siemens

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6
Q

current units

A

coulombs / sec = ampere (A)

1 A = 1 C/s

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7
Q

direct current

A

current flows in one continuous direction

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8
Q

alternating current

A

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

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9
Q

voltage (potential difference)

A
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10
Q

electromotive force (emf)

A

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

given in volts

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11
Q

voltage units

A

1 V = 1 J/C

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12
Q

Kirchhoff’s Junction Rule

A
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13
Q

Kirchhoff’s Loop Rule (?)

A

V source = V drop

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14
Q

resistance

A

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

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

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15
Q

conductors

A

materials that offer almost no resistance to current flow

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16
Q

insulators

A

materials that offer very high resistance to current flow

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17
Q

resistors

A

conductive materials that offer amounts of resistance between conductors and insulators

more conductive than insulators, less conductive than conductors

regulate current flow

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18
Q

characteristics that affect resistance of a resistor

A

resistivity, length, cross-sectional area, and temperature

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19
Q

resistance equation

A

R = ρL/A

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

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20
Q

resistivity (ρ)

A

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

21
Q

resistance and length

A

positive linear relationship

doubled length = doubled resistance

22
Q

cross-sectional area

A

inverse linear relationship

cross-sectional area doubled = resistance halved

23
Q

conduction pathways

A

a route for current to take through a resistor

a wider resistor has more conduction pathways within

24
Q

temperature and resistance

A

most conductors have higher resistance at higher temperatures

hot wire = more resistance

25
Q

Ohm’s Law equation

A

V = IR

V = voltage drog

I = current

R = magnitude of resistance

26
Q

current flows from ____ to ____

A

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

27
Q

secondary batteries

A

can be recharged

out outside source provides voltage to the positive end of the battery

28
Q

Power of resistor

A

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

29
Q

equivalent / resultant resistances (series)

A

the sum of the individual resistances

30
Q

equivalent resistance (resistors in parallel)

A

RP will always decrease as more resistors are added

31
Q

capacitor

A

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

32
Q

capacitor type covered on the MCAT

A

parallel plate capacitor

33
Q

capacitance equation

A

C = Q/V

Q = the magnitude of the charge stores on one plate

V = the voltage across the capacitor

34
Q

SI unit for capacitance

A

farad

1 F = 1 coulomb / volt

35
Q

capacitance of a parallel plate capacitor

A
36
Q

uniform electric field equation

A

E = V/d

37
Q

capacitor function

A

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

38
Q

potential energy store in a capacitor

A

U = ½ CV^2

39
Q

dielectric material

A

synonymous with insulator

40
Q

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

A

dielectric materials increase the capacitance of the capacitor

41
Q

dielectric constant (K)

A

a measure of a given materials insulating ability

a vacuum has a dielectric constant of 1

42
Q

capacitance due to a dielectric material

A

C’ = kC

C’ = the new capacitance with the dielectric present

C = the original capacitance

43
Q

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

A

decreases

44
Q

resultant capacitance of capacitors in parallel…

A

is equal to the sum of the individual capacitances

45
Q

meters

A

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

46
Q

ammeters

A

used to measure the current at some point within a circuit

(“am” → amp)

require a circuit to be active

47
Q

voltmeters

A

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

48
Q

ohmmeters

A

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