[L1] Current Resistance and Electromotive Force

current (i)

it is any motion of charge from one region to another

no current

when the motion of electron is random, there is ____ current

current

this requires net flow of charge in one direction

electric field

current is supplemented by ____, where it helps move electrons in a singular path

conventional current

this is treated as a flow of positive charges, regardless of whether the three charges in the conductor are positive, negative, or both

positive charges

conventional current is treated as a flow of ____, regardless of whether the three charges in the conductor are positive, negative, or both

current (it would still follow conventional current flow)

in a metallic conductor, the moving charges are electrons, but the ____ still points in the direction positive charges would flow

current

the direction in which there is a flow of positive charge

positive charge flow

we describe currents as though they consisted entirely of ____, even in cases in which we know that the actual current is due to electrons

conventional current

we describe currents as though they consisted entirely of positive charge flow, even in cases in which we know that the actual current is due to electrons. this is called ____

current (positive charge flow) is along direction of electric field

the main description of conventional current

current

it is the time rate of charge transfer through the cross-sectional area A

charge transfer, cross-sectional area

current is the time rate of ____ through the ____

scalar

current is a ____ quantity

the same

the current is in ____ direction as electric field whether the moving charges are positive or negative

ampere

the si unit for current

ampere (current)

defined to be one coulomb per second (C/s)

resistance

it is a measure of the opposition to current flow

ohm

si unit for resistance

resistivity (p)

it is a measure of the resistance of a given size of a specific material to electrical conduction

resistance, given size

resistivity is a measure of the ____ of a ____ of a specific material to electrical conduction

ohm * meter

unit for resistivity

directly proportional

resistance of an object is ____ to its length

inversely proportional

resistance of an object is ____ to its cross-sectional area

conductivity

it is the reciprocal of resistivity

resistivity

conductivity is the reciprocal of ____

(ohm * m)^-1

the unit for conductivity

larger

good conductors of electricity have ____ conductivity than insulators

low

a material with a ____ resistance has high conductivity

resistor

a circuit device made to have a specific value of resistance between its ends

resistance

resistor is a circuit device made to have a specific value of ____ between its ends

cylindrical, a few millimeters

individual resistors used in electronic circuitry are often ____, ____ in diameter in length, with wires coming out of the ends

3 or 4

the resistance of a resistor may be marked with a standard code using ____ bands near one end (how many)

refer to chart

enumerate the color code for resistors

digits

the first two bands of a resistor are ____

multiplier

the third band on a resistor is ____

tolerance

the fourth band on a resistor is ____

voltage

this is the potential energy per coulomb of charge available to electrons moving between terminals

voltage

this provides the “electric pressure” to move electrons between the terminals in a circuit

potential difference

there must be a large ____ between the ends of a long wire in order to cause a substantial electric current through the wire

there is no charge flow

if the ends of a conductor are at the same electric potential, then ____

charge flows from one end to another

if the ends of a conductor are at different electric potentials, then ____

ohm’s law

this states that electric current is proportional to voltage and inversely proportional to resistance

directly proportional

ohm’s law states that electric current is ____ to voltage

inversely proportional

ohm’s lae states that electric current is ____ to resistance

ohmic materials

materials that obey ohm’s law are called ____

linear

for ohmic material, the current-voltage graph is ____

I/R

for ohmic material, the slope is ____

nonlinear

for nonohmic material, the current-voltage graph is ____

voltage

this produces electric current

resistance

this opposes electric current

dc circuits (direct current)

these are characterized by current whose direction does not change

ac circuits (alternating current)

these are characterized by alternating current in which it oscillates back and forth

along the electric field. PE decreases

what is the natural flow of positive charges in an electric field? what will happen to its potential energy

electromotive force

the influence that makes current flow from lower to higher potential

lower to higher potential

electromotive force is the influence that makes current flow from ____ to ____

energy-per-unit charge quantity, just like epe

electromotive force is a poor term. it is not a force, but a ____ quantity

volt (same as epe)

the si unit for electromotive force

the same at the end of the round trip as at the beginning

if a charge q goes around a complete circuit and returns to its starting point, the potential energy must be ____

decrease

there is always a ____ in potential energy when charges move through an ordinary conducting material with resistance, so there must be some part of the circuit in which the potential energy increases

electromotive force

there is always a decrease in potential energy when charges move through an ordinary conducting material with resistance, so there must be some part of the circuit in which the potential energy increases. this is called

electric potential energy

sources of emfs (batteries, generators, etc.) convert energy of some form into ____ and transfer it into the circuit to which the device is connected

the same (because charge is conserved and it cannot accumulate in circuit devices)

current is ____ at every point in a simple loop

low

having a conductor with large area and shorter length will result into a ___ resistance to charge flow