Theme B Flashcards
Define thermal equilibrium
When there is no net heat flow between two objects.
State the zeroth law of thermodynamics
If two systems are in thermal equilibrium with a third system, they are in thermal equilibrium with each other
Define temperature
The quantity which is equal between two objects in thermal equilibrium, such that heat spontaneously flows from high to low temperature.
Define internal energy
The sum of the total kinetic energy of the particles in a system and the total potential energy due to intermolecular forces, between the particles in the system.
What is heat according to kinetic theory
The transfer of internal energy between systems due to difference in tempuratures
What is temperature according to kinetic theory
A measurement of average internal kinetic energy of a system
Define conduction
Heat transfer through the contact forces
Define convection
Heat transfer via fluid between objects
Radiation
Heat transfer via electromagnetic radiation
State the formula relating thermal conductivity and heat:
Where:
∆Q = heat (J)
∆t = duration
k = thermal conductivity
A = cross-sectional area
∆T = different in temperature between the ends of the solid
∆x = width
Define heat capacity
The heat required to increase the temperature of a system by one unit
State the formula for specific heat capacity
Where:
Q = heat
m = mass
c = specific heat capacity
∆T = change in temperature
Define latent heat
Heat which doesn’t result in a temperature change as it is resulting in a phase change.
State the formula for specific latent heat.
Where:
Q = heat
m = mass
L = specific latent heat
Define pressure
Perpendicular force per unit area over the surface of the system.
State the formula for pressure
Where:
P = pressure
F = force
A = area
Base SI units for pressure
Pascal, Pa
Pa = N⋅m⁻²
What is the unified atomic mass unit
One twelfth of the mass of a carbon-12 atom
State the equation for moles
Where:
n = amount of moles
N = number of particles
Na = Avogadro constant
Define molar mass
Mass per mole of a molecule
List the assumptions of an ideal gas
- Volume of the molecules are negligible to the volume of the gas
- Newtons laws of motion apply
- There are only inter-molecular forces during collisions
- The duration of a collision is negligible to the duration between collisions
- The collisions of molecules with each other are elastic
- The molecules move in random directions with a range of speeds
List the conditions of ideal
gases
- Low pressure
- High temperature
- Low density
State the combined gas law
Where:
P = pressure
V = volume
T = temperature (KELVIN)
State Avogadro’s law
At constant pressure and temperature, the volume occupied by a gas is directly proportional the number of molecules in the gas.
State the ideal gas law
Where:
P = pressure
V = volume
n = number of moles
R = gas constant
T = temperature
N = number of particles
kb = Boltzmann’s constant
State the equation of the pressure of an ideal gas
Where:
P = pressure
ρ = density
v = velocity of the molecules as they collide with the container
State the equation for average temperature
Where:
Eₖ = average kinetic energy
kb = Boltzmann’s constant
T = temperature
State the equations for internal energy of an ideal gas (all internal energy is kinetic)
Where:
U = internal energy (J)
n = number of moles
R = gas constant
T = temperature
N = number of particles
kb = Boltzmann’s constant
State the equation for electric current
Where:
I = current
∆q = charge
∆t = time
Another word for electric potential difference
Voltage
What is the coulomb in SI
C = A⋅s (ampere seconds)
Which charges flow in which direction of a current
Negative charges flow from low to high potential
State the equation for resistance
Where:
R = resistance
I = current
V = voltage
Base si unit of resistance
ohm, Ω = V⋅A⁻¹
Define resistance
Ratio of applied voltage across to the resultant current of a conductor
What do ohmic resistors follow
Ohms law, proportionality of current and voltage provided temperature is constant
The resistance of a conductor depends on:
- The length of the conductor
- The cross sectional area of the conductor
- The properties of the materials making up the conductor
State the equation for resistivity
Where:
R = resistance
ρ = density
A = cross sectional area
L = length
Where does resistivity originate from
Inelastic collisions of flowing electrons with the atoms of the conductor
State the equation for power developed in a conductor due to joule heating
Where:
P = power
I = current
V = voltage
R = resistance
What is emf
Energy transferred to a circuit per unit charge
Emf is not a force
Emf is not exactly voltage despite the unit
What is a cell
A component which creates a constant emf in a circuit. This emf establishes a potential difference across the cell called the terminal voltage.
Equation for emf
Where:
r = internal resistance
R = resistance
I = current
State Kirchhoff’s current law:
The total sum of the electric current into a junction is zero.
State Kirchhoff’s voltage law:
The total sum of the voltages around a loop is zero.
Ammeters series or parallel
Series
Do ideal ammeters have zero or infinite resistance
zero
