Q4: P6 L1&L2 Flashcards
any motion of charge from one region to another
Current
movement of negative charges (electrons) opposite to the direction of the electric field.
Electron Flow
the average velocity reached by charged particles such as electrons, in a material due to an electric field.
Drift Velocity
behaves as if the positive charge carriers cause current flow
conventional Current
current per unit cross-sectional area
Current density
a conducting path that forms a closed loop in which charges move
Electric Circuit
in the direction of F (f arrow) will result from the charged particle moving in vacuum, in which after some time the charged particle would be moving in that direction at high speed
Steady Acceleration
The current and current density don’t depend on the ____of the charge
sign
the resistance to the flow of an electric current with some materials resisting the current flow more than others
Resistivity
depends on the material of which the object is composed
Resistance
restricts the amount of electrical current which flows
Amount of Resistance
unit for resistivity
Ohmsxmeter
resistance=ohms
have highest resistivities
Insulator
one of the factors wherein the electrical resistance between 2 points can depend on.
Conductor’s length
Relationship between resistance and length
directly p
Relationship between resistance and area
inversely p
An electric circuit is complete only when
there is at least one closed loop from the positive to the negative end
Current is the amount of ____ that passes a given ____ in a given amount of _____
amount of charge that passes a given point in a given amount of time.
An ______ in a conductor causes charges to flow
electric field
positive same direction
negative opposite to Ef
Formula and unit for current
I=dQ/dt
C/s or Amp
Total charge moving past a given point is given by
dQ=nqvdAdt
formula for current given free electrons, drift velocity, and area
I=nqvdA
Formula and unit for current density
J=I/A
Amperes per square meter (Amp/m^2)
Good electrical conductors are often good ____ conductors, too
heat
Ohms Law states that
when a voltage (V) source is applied between two points in a circuit, an electrical current (I) will flow between them encouraged by the presence of the potential difference between these two points
The amount of electrical current which flows is restricted by ______
the amount of resistance (R) present.
the______ encourages the current to flow (the movement of charge), but it is_______ that discourages it
voltage; resistance
formula for Resistance
R=P(L/A)
Ohms
The electrical resistance between two points can depend on many factors such as
conductor’s length
its cross-sectional area
the temperature
the actual material from which it is made.
Ohms law tells us that for a given ______, the _____ flowing through the conductor is directly proportional to the _______
resistance,
current
applied voltage (I=V/R)
By connecting 2 conductors together in a series combination, we have effectively doubled _____ and ____ while the _____ remains the same
length
resistance
Cross-sectional area
by doubling the _____ and _____ of the conductor, to force the same current, we need to double the ________
length and resistance
applied voltage
By connecting 2 conductors in a parallel combination, we have effectively doubled ______ while _____ remains the same . We halved the total _____
Area
Length
Resistance
inverse of resistivity
electrical conductivity
conductivity of a material is presented by
1/P or 1/resistivity
Resistivity of metal vs resistivity of semiconductor in context of temp
metal - resistivity directly p to temp
semi - resistivity inversely p to temp
formula for resistivity with temp
P=P0(1+aT)
Formula for REsistance with temp
R=R0(1+aT)
Ohmic vs non ohmic materials
OHMIC
- ohms law
- linear r with c and v
- good conductors
- constant temp
NON
- not linear
- semiconductors
- doesnt work with constant temp
Ohms law states
that the current passing through a conductor is directly proportional to the voltage applied, provided that the temperature and other physical parameters remain constant.
Ohms law formula
V=IR
driving force of a device that keeps the constant flow of charges across circuit
Electromotive force
Formula for Electromotive force
E=W/Q
E (v or volts)
W (j or joules)
Q (coulomb)
work done to drive per unit charge across two points
electric potential difference
EMF VS PD
EMF
- max potential difference between 2 electrodes; open circuit
- independent of resistance
- used for source of current
-cause
PD
- difference of potential between 2 points in closed circuit
- depends upon resistance between 2 points and current
- can be measured between any 2 points
- Effect
