text stringlengths 2 2.33k | source stringclasses 826
values |
|---|---|
The dielectric strength of an insulator represents a critical value of electrical field at which the molecules in an insulating material start to become ionized. When this happens, the material can conduct and dielectric breakdown is observed. | https://openstax.org/books/university-physics-volume-2/pages/8-summary |
I ave = Î Q Î t I ave = Î Q Î t | https://openstax.org/books/university-physics-volume-2/pages/9-key-equations |
1 A = 1 C/s 1 A = 1 C/s | https://openstax.org/books/university-physics-volume-2/pages/9-key-equations |
I = d Q d t I = d Q d t | https://openstax.org/books/university-physics-volume-2/pages/9-key-equations |
v d = I n q A v d = I n q A | https://openstax.org/books/university-physics-volume-2/pages/9-key-equations |
I = ⬠area J â · d A â I = ⬠area J â · d A â | https://openstax.org/books/university-physics-volume-2/pages/9-key-equations |
Ï = E J Ï = E J | https://openstax.org/books/university-physics-volume-2/pages/9-key-equations |
V = I R V = I R | https://openstax.org/books/university-physics-volume-2/pages/9-key-equations |
Ï = Ï 0 [ 1 + α ( T â T 0 ) ] Ï = Ï 0 [ 1 + α ( T â T 0 ) ] | https://openstax.org/books/university-physics-volume-2/pages/9-key-equations |
R = Ï L A R = Ï L A | https://openstax.org/books/university-physics-volume-2/pages/9-key-equations |
R = R 0 ( 1 + α ΠT ) R = R 0 ( 1 + α ΠT ) | https://openstax.org/books/university-physics-volume-2/pages/9-key-equations |
P = I V P = I V | https://openstax.org/books/university-physics-volume-2/pages/9-key-equations |
P = I 2 R = V 2 R P = I 2 R = V 2 R | https://openstax.org/books/university-physics-volume-2/pages/9-key-equations |
ampere (amp) : SI unit for current;1A=1C/s1A=1C/s | https://openstax.org/books/university-physics-volume-2/pages/9-key-terms |
circuit : complete path that an electrical current travels along | https://openstax.org/books/university-physics-volume-2/pages/9-key-terms |
conventional current : current that flows through a circuit from the positive terminal of a battery through the circuit to the negative terminal of the battery | https://openstax.org/books/university-physics-volume-2/pages/9-key-terms |
critical temperature : temperature at which a material reaches superconductivity | https://openstax.org/books/university-physics-volume-2/pages/9-key-terms |
current density : flow of charge through a cross-sectional area divided by the area | https://openstax.org/books/university-physics-volume-2/pages/9-key-terms |
diode : nonohmic circuit device that allows current flow in only one direction | https://openstax.org/books/university-physics-volume-2/pages/9-key-terms |
drift velocity : velocity of a charge as it moves nearly randomly through a conductor, experiencing multiple collisions, averaged over a length of a conductor, whose magnitude is the length of conductor traveled divided by the time it takes for the charges to travel the length | https://openstax.org/books/university-physics-volume-2/pages/9-key-terms |
electrical conductivity : measure of a materialâs ability to conduct or transmit electricity | https://openstax.org/books/university-physics-volume-2/pages/9-key-terms |
electrical current : rate at which charge flows,I=dQdtI=dQdt | https://openstax.org/books/university-physics-volume-2/pages/9-key-terms |
electrical power : time rate of change of energy in an electric circuit | https://openstax.org/books/university-physics-volume-2/pages/9-key-terms |
Josephson junction : junction of two pieces of superconducting material separated by a thin layer of insulating material, which can carry a supercurrent | https://openstax.org/books/university-physics-volume-2/pages/9-key-terms |
Meissner effect : phenomenon that occurs in a superconducting material where all magnetic fields are expelled | https://openstax.org/books/university-physics-volume-2/pages/9-key-terms |
nonohmic : type of a material for which Ohmâs law is not valid | https://openstax.org/books/university-physics-volume-2/pages/9-key-terms |
ohm : (Ω)(Ω)unit of electrical resistance,1Ω=1V/A1Ω=1V/A | https://openstax.org/books/university-physics-volume-2/pages/9-key-terms |
Ohmâs law : empirical relation stating that the currentIis proportional to the potential differenceV; it is often written asV=IRV=IR, whereRis the resistance | https://openstax.org/books/university-physics-volume-2/pages/9-key-terms |
ohmic : type of a material for which Ohmâs law is valid, that is, the voltage drop across the device is equal to the current times the resistance | https://openstax.org/books/university-physics-volume-2/pages/9-key-terms |
resistance : electric property that impedes current; for ohmic materials, it is the ratio of voltage to current,R=V/IR=V/I | https://openstax.org/books/university-physics-volume-2/pages/9-key-terms |
resistivity : intrinsic property of a material, independent of its shape or size, directly proportional to the resistance, denoted byÏÏ | https://openstax.org/books/university-physics-volume-2/pages/9-key-terms |
schematic : graphical representation of a circuit using standardized symbols for components and solid lines for the wire connecting the components | https://openstax.org/books/university-physics-volume-2/pages/9-key-terms |
SQUID : (Superconducting Quantum Interference Device) device that is a very sensitive magnetometer, used to measure extremely subtle magnetic fields | https://openstax.org/books/university-physics-volume-2/pages/9-key-terms |
superconductivity : phenomenon that occurs in some materials where the resistance goes to exactly zero and all magnetic fields are expelled, which occurs dramatically at some low critical temperature(TC)(TC) | https://openstax.org/books/university-physics-volume-2/pages/9-key-terms |
The average electrical currentIaveIaveis the rate at which charge flows, given byIave=ÎQÎtIave=ÎQÎt, whereÎQÎQis the amount of charge passing through an area in timeÎtÎt. | https://openstax.org/books/university-physics-volume-2/pages/9-summary |
The instantaneous electrical current, or simply the currentI, is the rate at which charge flows. Taking the limit as the change in time approaches zero, we haveI=dQdtI=dQdt, wheredQdtdQdtis the time derivative of the charge. | https://openstax.org/books/university-physics-volume-2/pages/9-summary |
The direction of conventional current is taken as the direction in which positive charge moves. In a simple direct-current (DC) circuit, this will be from the positive terminal of the battery to the negative terminal. | https://openstax.org/books/university-physics-volume-2/pages/9-summary |
The SI unit for current is the ampere, or simply the amp (A), where1A=1C/s1A=1C/s. | https://openstax.org/books/university-physics-volume-2/pages/9-summary |
Current consists of the flow of free charges, such as electrons, protons, and ions. | https://openstax.org/books/university-physics-volume-2/pages/9-summary |
The current through a conductor depends mainly on the motion of free electrons. | https://openstax.org/books/university-physics-volume-2/pages/9-summary |
When an electrical field is applied to a conductor, the free electrons in a conductor do not move through a conductor at a constant speed and direction; instead, the motion is almost random due to collisions with atoms and other free electrons. | https://openstax.org/books/university-physics-volume-2/pages/9-summary |
Even though the electrons move in a nearly random fashion, when an electrical field is applied to the conductor, the overall velocity of the electrons can be defined in terms of a drift velocity. | https://openstax.org/books/university-physics-volume-2/pages/9-summary |
The current density is a vector quantity defined as the current through an infinitesimal area divided by the area. | https://openstax.org/books/university-physics-volume-2/pages/9-summary |
The current can be found from the current density,I=â¬areaJâ·dAâI=â¬areaJâ·dAâ. | https://openstax.org/books/university-physics-volume-2/pages/9-summary |
An incandescent light bulb is a filament of wire enclosed in a glass bulb that is partially evacuated. Current runs through the filament, where the electrical energy is converted to light and heat. | https://openstax.org/books/university-physics-volume-2/pages/9-summary |
Resistance has units of ohms(Ω)(Ω), related to volts and amperes by1Ω=1V/A1Ω=1V/A. | https://openstax.org/books/university-physics-volume-2/pages/9-summary |
The resistanceRof a cylinder of lengthLand cross-sectional areaAisR=ÏLAR=ÏLA, whereÏÏis the resistivity of the material. | https://openstax.org/books/university-physics-volume-2/pages/9-summary |
Values ofÏÏinTable 9.1show that materials fall into three groupsâconductors, semiconductors, and insulators. | https://openstax.org/books/university-physics-volume-2/pages/9-summary |
Temperature affects resistivity; for relatively small temperature changesÎTÎT, resistivity isÏ=Ï0(1+αÎT)Ï=Ï0(1+αÎT), whereÏ0Ï0is the original resistivity andααis the temperature coefficient of resistivity. | https://openstax.org/books/university-physics-volume-2/pages/9-summary |
The resistanceRof an object also varies with temperature:R=R0(1+αÎT)R=R0(1+αÎT), whereR0R0is the original resistance, andRis the resistance after the temperature change. | https://openstax.org/books/university-physics-volume-2/pages/9-summary |
Ohmâs law is an empirical relationship for current, voltage, and resistance for some common types of circuit elements, including resistors. It does not apply to other devices, such as diodes. | https://openstax.org/books/university-physics-volume-2/pages/9-summary |
One statement of Ohmâs law gives the relationship among currentI, voltageV, and resistanceRin a simple circuit asV=IRV=IR. | https://openstax.org/books/university-physics-volume-2/pages/9-summary |
Another statement of Ohmâs law, on a microscopic level, isJ=ÏEJ=ÏE. | https://openstax.org/books/university-physics-volume-2/pages/9-summary |
Electric power is the rate at which electric energy is supplied to a circuit or consumed by a load. | https://openstax.org/books/university-physics-volume-2/pages/9-summary |
Power dissipated by a resistor depends on the square of the current through the resistor and is equal toP=I2R=V2RP=I2R=V2R. | https://openstax.org/books/university-physics-volume-2/pages/9-summary |
The SI unit for electric power is the watt and the SI unit for electric energy is the joule. Another common unit for electric energy, used by power companies, is the kilowatt-hour (kW··h). | https://openstax.org/books/university-physics-volume-2/pages/9-summary |
The total energy used over a time interval can be found byE=â«PdtE=â«Pdt. | https://openstax.org/books/university-physics-volume-2/pages/9-summary |
Superconductivity is a phenomenon that occurs in some materials when cooled to very low critical temperatures, resulting in a resistance of exactly zero and the expulsion of all magnetic fields. | https://openstax.org/books/university-physics-volume-2/pages/9-summary |
Materials that are normally good conductors (such as copper, gold, and silver) do not experience superconductivity. | https://openstax.org/books/university-physics-volume-2/pages/9-summary |
Superconductivity was first observed in mercury by Heike Kamerlingh Onnes in 1911. In 1986, Dr. Ching Wu Chu of Houston University fabricated a brittle, ceramic compound with a critical temperature close to the temperature of liquid nitrogen. | https://openstax.org/books/university-physics-volume-2/pages/9-summary |
Superconductivity can be used in the manufacture of superconducting magnets for use in MRIs and high-speed, levitated trains. | https://openstax.org/books/university-physics-volume-2/pages/9-summary |
V terminal = ε â I r eq V terminal = ε â I r eq | https://openstax.org/books/university-physics-volume-2/pages/10-key-equations |
R eq = R 1 + R 2 + R 3 + ⯠+ R N â 1 + R N = â i = 1 N R i R eq = R 1 + R 2 + R 3 + ⯠+ R N â 1 + R N = â i = 1 N R i | https://openstax.org/books/university-physics-volume-2/pages/10-key-equations |
R eq = ( 1 R 1 + 1 R 2 + ⯠+ 1 R N ) â1 = ( â i = 1 N 1 R i ) â1 R eq = ( 1 R 1 + 1 R 2 + ⯠+ 1 R N ) â1 = ( â i = 1 N 1 R i ) â1 | https://openstax.org/books/university-physics-volume-2/pages/10-key-equations |
â I in = â I out â I in = â I out | https://openstax.org/books/university-physics-volume-2/pages/10-key-equations |
â V = 0 â V = 0 | https://openstax.org/books/university-physics-volume-2/pages/10-key-equations |
V terminal = â i = 1 N ε i â I â i = 1 N r i = â i = 1 N ε i â I r eq V terminal = â i = 1 N ε i â I â i = 1 N r i = â i = 1 N ε i â I r eq | https://openstax.org/books/university-physics-volume-2/pages/10-key-equations |
V terminal = ε â I â i = 1 N ( 1 r i ) â1 = ε â I r eq V terminal = ε â I â i = 1 N ( 1 r i ) â1 = ε â I r eq | https://openstax.org/books/university-physics-volume-2/pages/10-key-equations |
q ( t ) = C ε ( 1 â e â t R C ) = Q ( 1 â e â t Ï ) q ( t ) = C ε ( 1 â e â t R C ) = Q ( 1 â e â t Ï ) | https://openstax.org/books/university-physics-volume-2/pages/10-key-equations |
Ï = R C Ï = R C | https://openstax.org/books/university-physics-volume-2/pages/10-key-equations |
I = ε R e â t R C = I o e â t R C I = ε R e â t R C = I o e â t R C | https://openstax.org/books/university-physics-volume-2/pages/10-key-equations |
q ( t ) = Q e â t Ï q ( t ) = Q e â t Ï | https://openstax.org/books/university-physics-volume-2/pages/10-key-equations |
I ( t ) = â Q R C e â t Ï I ( t ) = â Q R C e â t Ï | https://openstax.org/books/university-physics-volume-2/pages/10-key-equations |
ammeter : instrument that measures current | https://openstax.org/books/university-physics-volume-2/pages/10-key-terms |
electromotive force (emf) : energy produced per unit charge, drawn from a source that produces an electrical current | https://openstax.org/books/university-physics-volume-2/pages/10-key-terms |
equivalent resistance : resistance of a combination of resistors; it can be thought of as the resistance of a single resistor that can replace a combination of resistors in a series and/or parallel circuit | https://openstax.org/books/university-physics-volume-2/pages/10-key-terms |
internal resistance : amount of resistance to the flow of current within the voltage source | https://openstax.org/books/university-physics-volume-2/pages/10-key-terms |
junction rule : sum of all currents entering a junction must equal the sum of all currents leaving the junction | https://openstax.org/books/university-physics-volume-2/pages/10-key-terms |
Kirchhoffâs rules : set of two rules governing current and changes in potential in an electric circuit | https://openstax.org/books/university-physics-volume-2/pages/10-key-terms |
loop rule : algebraic sum of changes in potential around any closed circuit path (loop) must be zero | https://openstax.org/books/university-physics-volume-2/pages/10-key-terms |
potential difference : difference in electric potential between two points in an electric circuit, measured in volts | https://openstax.org/books/university-physics-volume-2/pages/10-key-terms |
potential drop : loss of electric potential energy as a current travels across a resistor, wire, or other component | https://openstax.org/books/university-physics-volume-2/pages/10-key-terms |
RCcircuit : circuit that contains both a resistor and a capacitor | https://openstax.org/books/university-physics-volume-2/pages/10-key-terms |
shock hazard : hazard in which an electric current passes through a person | https://openstax.org/books/university-physics-volume-2/pages/10-key-terms |
terminal voltage : potential difference measured across the terminals of a source when there is no load attached | https://openstax.org/books/university-physics-volume-2/pages/10-key-terms |
thermal hazard : hazard in which an excessive electric current causes undesired thermal effects | https://openstax.org/books/university-physics-volume-2/pages/10-key-terms |
three-wire system : wiring system used at present for safety reasons, with live, neutral, and ground wires | https://openstax.org/books/university-physics-volume-2/pages/10-key-terms |
voltmeter : instrument that measures voltage | https://openstax.org/books/university-physics-volume-2/pages/10-key-terms |
All voltage sources have two fundamental parts: a source of electrical energy that has a characteristic electromotive force (emf), and an internal resistancer. The emf is the work done per charge to keep the potential difference of a source constant. The emf is equal to the potential difference across the terminals whe... | https://openstax.org/books/university-physics-volume-2/pages/10-summary |
The voltage output of a device is called its terminal voltageVterminalVterminaland is given byVterminal=뵉IrVterminal=뵉Ir, whereIis the electric current and is positive when flowing away from the positive terminal of the voltage source andris the internal resistance. | https://openstax.org/books/university-physics-volume-2/pages/10-summary |
The equivalent resistance of an electrical circuit with resistors wired in a series is the sum of the individual resistances:Rs=R1+R2+R3+â¯=âi=1NRiRs=R1+R2+R3+â¯=âi=1NRi. | https://openstax.org/books/university-physics-volume-2/pages/10-summary |
Each resistor in a series circuit has the same amount of current flowing through it. | https://openstax.org/books/university-physics-volume-2/pages/10-summary |
The potential drop, or power dissipation, across each individual resistor in a series is different, and their combined total is the power source input. | https://openstax.org/books/university-physics-volume-2/pages/10-summary |
The equivalent resistance of an electrical circuit with resistors wired in parallel is less than the lowest resistance of any of the components and can be determined using the formulaReq=(1R1+1R2+1R3+â¯)â1=(âi=1N1Ri)â1.Req=(1R1+1R2+1R3+â¯)â1=(âi=1N1Ri)â1. | https://openstax.org/books/university-physics-volume-2/pages/10-summary |
Each resistor in a parallel circuit has the same full voltage of the source applied to it. | https://openstax.org/books/university-physics-volume-2/pages/10-summary |
The current flowing through each resistor in a parallel circuit is different, depending on the resistance. | https://openstax.org/books/university-physics-volume-2/pages/10-summary |
If a more complex connection of resistors is a combination of series and parallel, it can be reduced to a single equivalent resistance by identifying its various parts as series or parallel, reducing each to its equivalent, and continuing until a single resistance is eventually reached. | https://openstax.org/books/university-physics-volume-2/pages/10-summary |
Kirchhoffâs rules can be used to analyze any circuit, simple or complex. The simpler series and parallel connection rules are special cases of Kirchhoffâs rules. | https://openstax.org/books/university-physics-volume-2/pages/10-summary |
Kirchhoffâs first rule, also known as the junction rule, applies to the charge to a junction. Current is the flow of charge; thus, whatever charge flows into the junction must flow out. | https://openstax.org/books/university-physics-volume-2/pages/10-summary |
Kirchhoffâs second rule, also known as the loop rule, states that the voltage drop around a loop is zero. | https://openstax.org/books/university-physics-volume-2/pages/10-summary |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.