Electrical Charge Transfer Flashcards
P.D definition
the amount of energy transferred from electrical to other forms of energy per unit charge
resistance definition
the amount of opposition against current & equatioon
coulomb definiiton
the charge in a current powered by 1V
what happens to resistance in a parralel circuit
resistance decreases, due to increase in branches
what is the definition of drift velocity
the average velocity of electrons when there is an APPLIED ELECTRIC FIELD
number density units
m^-3
what is conventional current
the flow of positive charge, from the positive terminal to the negative terminal
electron flow definition
the flow of negative charge from the negative terminal to the positive terminal
what does Kirchoff’s first law prove: conservation of…
conservation of charge
definition of e.m.f
The energy transferred from chemical to electrical per unit charge
definition of p.d
The energy transferred from electrical energy to other forms (e.g heat, light) per unit charge
what does the gradient of a IV-characteristic graph represent?
1/resistance
ohms law definition
p.d is directly proportional to current, assuming TEMPERATURE OF CONDUCTOR IS CONSTANT
how is ohms law represented on a graph?
straight line which passes through origin
name 3 ways to change resistance of a wire in a circuit
type of material, shape of wire, temperature of wire
resistivity equation
resistance = (resistivity * length ) / area
units for resistivity
ohm meters
resistance defintiion
write R= I/V in words and say ‘ the amount of opposition against current’
resistivity definition
write the equation & “a measure of how strongly a material opposes the flow of current”
what is extraneous light (LDR section)
light from an exteral light source
what happens to a NTC thermistor when there’s a rise in temperature?
releases more charge carriers, hence reducing the resistance. The increase in vibrations of particles has a lower impact on the resistance - net decrease in charge.
what are the 2 things that could happen in a component that could impact its resistance when temperature increases
- increase in number of charge carriers - decrease resistance
- increase in vibrations (of positive ions) leads to more collisions - increasing resistance
for a NTC thermistor, when temperature increases, resistance …
decreases
for an LDR, when light intensity increases, resistance ….
decreases
What does ‘e’ stand for
Elementary charge - charge on 1 electron
what is Kirchoff’s first law?
the sum of current entering a junction is equal to the sum of the current exiting it
current definition
rate of flow of charge
what is the charge of a single electron (e)? single proton?
electron: 1.6x10^-19
proton: 1.6x10^19
number density definition
no. of free electrons per m^3 of a specific material
what is an electron gun used fore?
A device that uses a large accelerating p.d to produce a narrow beam of electrons
how do electron guns work
small metal filament is kept in a vacuum with a high p.d. (1)
It is heated by electric current. (2)
Some electrons gain enough K.E to escape metal and accelerate to anode. (3)
light intensity units and equation?
lux; l is directly proportional to 1/distance^2`
give a similarities between thermistor and LDR
when temp/ligth intensity increases, resistance decreases
are thermistors and LDR’s conductors, semi-conductors or insulators?
semi-conductors
which of these has highest number density: insulators, semi-conductors, conductors
conductors
what is the mass of an electron
9.11x10^-31
true or false, thermistors and LDR’s are ohmic conductors
false
describe the structure of metal (in a wire)
a regular crystal structure of postive ions surrounded by a no. of free electrons
what material is often used in computer processors and why?
silicon because it’s a good semi-conductor
conservation of charge definition
the net charge must be the same before and after an interaction; charge carriers can’t be created or destroyed
what does the gradient of an IV graph represent
1/resistance
name 3 things that could impact resistance in a circuit
type of material, shape of material, temperature of wire
IV characteristic of thermistor? of LDR?
search it up
electronvolt defintiion
A unit of energy. (1) the energy transfered to or from an electron when it passes theough a p.d of 1 volt. 1eV = 1.6x10^-19J
1eV is equal to … J
1.6x10^-19J
what is the equation of eV
eV=1/2mv^2
what happens to electrons eneergy in electron gun/cathode ray tube when p.d increases
increase in energy = increase in speed of leectons
what will happen to electrons speed in a cathode ray tube/ electron gun when there’s no p.d?
speed of electron will be constant (not stationary)
where does electron accelerate in cathode ray tube? where is the speed constant?
accelerates between anode and cathode
constant between anode and screen
what are the advantages of using a data logger (4)
1) continuous record for a long time scale
2) records v.short time scale
3) automatic recording
4) data can be fed into computer for analysis
