Karteikarten
Physics Flashcards unit 1
Karten in diesem Stapel (34)
- 1Explain pair productionPhoton interacts with atom
Energy of photon used to create particle antiparticle pair - 2What roles do exchange particles play in interactionsTransfer...
Energy, momentum, force and sometimes charge - 3Electron VoltThe kinetic energy gained by an electron when it is accelerated through a potential difference of 1 volt
- 4Ohmic conductorV is directly proportional to I
or
Constant resistance - 5Principle property of superconductorA material which has zero resistance
- 6Definition of an excited atomOrbital electron is at higher energy level than ground state
- 7Difference between a Hadron and LeptonLeptons don't experience strong interaction
Hadrons are not fundamental particles - 8What happens to positron produced by pair productionEncounters another electron
They annihilate
Two high energy photons released - 9What is meant by Root mean square voltageThe equivalent dc voltage that produces the same heating effect
- 10Why does current of a lamp decrease after initial increaseResistance of filament increases
because
temperature of filament increases
so
current decreases - 11What happens to excess energy of photon in pair productionTurns into kinetic energy of photon
- 12Why are different energies of photons possible when electron de-excitesThe electron returns to lower energy level by a different route
- 13Range of Strong Nuclear ForceAttractive 3-4 femtometres
Repulsive within 0.5 fm
(femtometres = ^ -15 metres) - 14Define a HadronAny particle or antiparticle that can interact though the strong interaction
- 15Define emfElectrical energy per unit charge produced
- 16When is max power delivered to loadLoad resistance = Source resistane
- 17Work FunctionThe work function of a metal is the minimum kinetic energy needed by an electron to escape the surface of a metal
- 18Internal Resistance of batteryThe resistance of the material within the battery
- 19Electron CaptureOrbital electron interacts with proton in the nucleus via weak interaction to form a neutron and electron nuetrino
- 20Explain why kinetic energy of emitted electron has a max valueElectrons energy comes from absorption of photon. Energy required for electron varies as surface electrons require less energy. These electrons have max energy.
- 21Explain why below a certain value electrons are not emittedWork function is the min energy needed to release an electron. Below a certain frequency, energy of photon is less than work function.
- 22Why is the fact that there is no time delay is importantShows light must travel as photons which transfer energy in discrete packets
- 23Explain the threshold frequencyThreshold frequency is the min frequency for emission of electron. If below this value no emission even if intensity increased because the energy of photon is less than the work function.
- 24Explain why an electron moves from ground state to n=2 in excitationElectron absorbs energy from incident electron. This ____ exact value is needed to make the transition
- 25Why are electrons release from the metal surfaceLight consists of photons of energy hf. An electron at the surface of metal can only gain the energy of a single photon when it interacts with one. The work function of a metal is...Therefore elctron escapes metal if hf is greater than work function.
- 26Why is it important to test by experiment a scientific theoryIf a reliable experiment does not support a hypothesis then the hypothesis must be changed
- 27Internal resistance of a batteryThe resistance of the material within a battery
- 28What is the terminal voltageVoltage across the circuit
- 29Explain why emitted electrons have a range of KEEnergy is required to leave surface of metal. Max KE is hf - work function. The deeper the electrons the more energy is used to get to the surface
- 30Ground stateWhen electrons in their lowest energy state/ most stable state
- 31Excitation vs. IonisationBoth require the right amount of energy
Excitation promotes electron to higher energy level
Ionisation - electron receives enough energy to leave the atom - 32Why do photons of certain frequencies cause excitation in particular atomElectrons occupy discrete energy levels
Need to absorb exact amount of energy to move to higher energy level
Photons need to be of certain frequency
All energy of photon is absorbed in 1 to 1 interaction - 33Explain what must happen in order for a new scientific theory to replace old oneTheory makes prediction tested by other scientists
- 34Measuring voltage using osciliscopeConnect power supply to the input of the oscilloscope
Time base switched off
Adjust y gain until complete vertical line seen and measure. Convert by calibration.
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- Karteikarten am Physics Flashcards unit 1, erstellt von Husein Essaji am 20/04/2015.
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- Husein Essaji
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