thermal energy Flashcards
What is Avogadro’s constant in words
The number of atoms, molecules, or particles in one mole of a substance, which is approximately
6.022×10^23
what is the internal energy of a ideal gas
total kinetic energy of the particles
explain how the energy transferred to the ample changes the arrangement of atoms during the time ta to tb (this is during change of state) june 2020 paper 2
temperature is constant … temperature transferred breaks some bonds between atoms,
describe how the motion of the atom changes during its liquid state ? (from solid to liquid)
the temperature increases there fore the mean kinetic energy of atoms increases
difference between specific latent heat of fusion and Vaporisation?
Fusion = solid ⇌ liquid
Vaporisation = liquid ⇌ gas
when ever you see a question talking about charged particles being accelerated through a pd what’s the first equation you will write?
eV=KE => eV=1/2mv^2
Discuss how the masses of ions can be deduced from the measurement of time intervals
a=F/m Therefore smaller mass higher acceleration there fore higher speed.
ways to make the uncertainty in the value of the time constant more accurate in a oscilloscope?
reduce the time base to make resolutions smaller….
Uncertainty is due to the smallness of the divisions and this
action means the waveform/trace stretched horizontally/in
x-direction.
reduce y-gain….Uncertainty is due to the smallness of the divisions and this
action means the waveform/trace stretched vertically/in ydirection. (The trace will need to be moved vertically to fit
on the screen)
A thermal nuclear reactor uses enriched uranium as its fuel. This is fuel in which the ratio of U-235 to U-238 has been artificially increased from that found in naturally-occurring ore.
Describe what happens when neutrons interact with U-235 and U-238 nuclei in a thermal nuclear reactor.
U-235 (absorbs) a neutron to become U-236,which is unstable and decays into two daughter nuclei and 2 or 3 neutrons
U-238 absorbs neutrons without undergoing fission.it just sits there or scatters neutrons
what’s an alternating current or voltage
its one that changes direction with time
Lenz law
the direction of induced emf will always oppose or tend to oppose the flux change producing it
what’s a direct current?
flows in one direction
why are transformers not 100 percent efficient
we got flux slushing around the iron core and iron core is a conductor therefore we will get an induced emf in the iron core which would produce eddy current and what they will do from lenz’s law is they will produce a magnetic field which would oppose the original magnetic field in the opposite direction so your going to end up with less flux and also the eddy currents will have their own heating effect .
What kind of magnetic field is produced inside a coil(solenoid) ?
uniform magnetic field inside the coil, with circular fields around each individual wire loop.
What kind of magnetic field is produced inside a wire?
Circular magnetic field around the wire.
what would increase the amplitude of an induced emf?
greater number of coils ,larger surface area , higher frequency of rotation
define tesla
the tesla is the magnetic field strength that would produce a force of 1 NEWTON PER METRE on a current of 1 AMP perpendicular to it.
A current carrying conductor in a magnetic field experiences a force. What does the size of the force depend on?
F=BIL COS THETA
the field strength
the current
the length of the conductor perpendicular to the field
state Lenz law and use it to explain why Bart must work harder when he is using the dynamo on his bike to power his lights.
Lenz law states that an induced emf will oppose or tend to oppose the flux change causing it.
As the coil in the dynamo rotates inside a magnetic field an emf is induced in the coil and a current flows in the coil.
from Lenz law this emf will oppose the flux cutting that produces it
The induced current in the coil will produce a field that will oppose the field of the dynamo magnets.
This forces Bart to do work
From the conservation of energy the energy to light the bulb must come from somewhere
Discuss how Lenz law is consistent with the principle of conservation of energy.
As a magnet falls through a copper tube (a conductor), it cuts through magnetic flux, inducing a current (Faraday’s Law). This induced current creates a magnetic field that opposes the motion of the magnet (Lenz’s Law), slowing it down. If this opposing field didn’t exist, the magnet would accelerate continuously, generating infinite current and violating the conservation of energy. Instead, the magnet loses kinetic energy, which is transferred into electrical energy in the copper. Due to the resistance in the copper, this electrical energy is dissipated as thermal energy (Joule heating), ensuring that energy is conserved and not created from nothing.
