Flashcards
Modern Physics Handy Hints / Study
Flashcards do conjunto (23)
- 1Explain Photocurrent in relation to the Photoelectric Effect.The Photoelectric Effect is shining light onto a metal surface causes photoelectron to be emitted. Because of this, the current that flows through the material is known as a the photocurrent.
- 2Explain the Stopping VoltageIs the opposing Voltage (or minimum potential difference) needed to prevent/stop current from flowing.
Ek = eVs - 3Explain the Kinetic Energy vs Frequency Graph- The graph shows that only photons above a certain frequency (fo) will release electrons with kinetic energy (Ek).
- Since the energy (E) of the incident photons (light) is determined by E = hf, the gradient (m) = h (Plank's constant)
- Extending the line back to the y-intercept shows the energy required to overcome bonds holding the electron to the surface (the work function) of the material. - 4Kinetic Energy vs Frequency Graph - Explain the formulashf = work + Ek -> Ek = hf - work
y = mx + c -> Ek = hf - work
m = h (Planck's constant)
m Line meeting f = fo (threshold frequency)
y-intercept = work function - 5Particle Model of Light- Light comes in small packages/ quanta called photons
- The higher the f, the higher the E
- Blue light has higher f than red light
- The brightness of a light depends on the amount of electrons emitted
- Each photon gives an electron a certain amount of E. If there is enough E then the electron will be emitted. Extra E means electrons will be emitted with Ek. - 6Equations involved in the Photoelectric EffectE = hf
hf = work + Ek
Ek = hf - work
v or c = fy
f = c / y - 7Elements, explain A X ZA = Mass Number
= Number of nucleons in a nucleus
(Bigger number)
Z = Element
Z = Atomic Number
= Number of Protons in a nucleus
(smaller number) - 8How do you find the number of neutrons? A X ZA = number of nucleons - Z = number of protons = number of neutrons
A - Z = neutrons - 9change in m / mass defect calculation is...= mi - mf
= mreactants - mproducts
= mprotons + mneutrons - mnucleus
(one element^) - 10Mass Defect Definition:The difference in mass between an atom and the sum of the masses of the protons, neutrons, and electrons in the atom.
- 11Binding Energy definitionE = mc2
The energy required to break up the nucleus of an atom. And or the energy released when the nucleus is formed.
It is equal to the mass defect. - 12Energy Released is....The lost mass/mass defect is converted to the energy released.
- Conservation of mass & energy - 13Explain FissionThe splitting of large unstable nuclei into smaller more stable nuclei.
- 14Explain FusionThe joining of smaller nuclei into larger nuclei.
- 15In both Fission & Fusion- BEPN increases
- Nucleons have less Energy
- Mass decreases
- Energy is released - 16Line Spectrum= Absorption & Emmission Spectrum
( Electron absorbing and emitting photons to change E levels/states )
When element gases are excited (by a large Voltage) and observed through a diffraction grating they show specific lines at certain frequencies.
- Each element has their own signature set of lines
- Huge gapes, gas under low pressure, a few y - 17Continuous SpectrumWhen you shine light through a prism and there's a rainbow = dispersion.
This happens because light of different wavelengths (colours) refracts (bends) at different angles when passing through a prism.
- The rainbow is a 'spectrum' and if it contains all colours from red to violet with no gaps, it is a continuous spectrum.
- Gas under high pressure, all y - 18Explanation of SeriesLyman, s = 1 L = (3+) -> Ultra Violet
Balmer, s = 2 L = (3+) -> VISIBLE
Paschen, s = 3 L = (4+) -> Infrared - 19Excited StateWhen an electron jumps from its original E level / orbital (GS) to a higher E level further from the nucleus.
- When an electron is excited, it is no longer bound to the atom -> becoming an ion. - 20IonisationWhen an electron is excited, it is no longer bound to an atom, becoming an ion.
This is called the "ionisation energy level"
As all the E is used to overcome the attractive force to the nucleus.
E = 0 J
- The amount of E required for an electron to completely leave an atom. - 21How to find y - interceptwork / electron charge = y-intercept
- 22How to find the gradienth / electron charge = m
- 23BEPN is.........The greater the BEPN the more stable the nucleus is (as it takes more energy to break up) & the lower the mass.
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- NCEA Level 3 physics level 3 (Modern Physics!!!) FlashCards sobre Modern Physics Handy Hints / Study , criado por Humayra Azam em 14-03-2021.
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- Humayra Azam
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