with 100% Correct Answer 2024 update
Electron Gun Model Answer Correct Answer - Low voltage supply heats filament causes
thermionic emission/ electrons have enough energy to leave
- Electrons are repulsed from the cathode (filament) and attracted towards the anode
- This electric field causes electrons to accelerate
- There is a hole in the anode which creates a beam for electrons that pass through
- Electrons are then fired through a vacuum (to stop interfering particles) onto a
fluorescent screen
Photo Electric Effect Model Answer Correct Answer - 1 Electron near the surface of a
metal gains 1 photon and gains enough energy to be liberated
- The work function is the energy needed for the electron to escape the surface
- increasing intensity will increase the number of photons
- increasing frequency will increase the energy of the photons
- These electrons released are called photoelectrons
- This effect can be explained through E = hf
PhotoElectric Equation Correct Answer Ekmax = hf - work fucntion
Ekmax = max kinetic energy of freed electrons
hf = energy of photon
work function = the minimum energy to release an electron
Why does the photoelectric effect equation refer to kinetic energy as maximum kinetic
energy? Correct Answer It will not always be an equal energy transfer:
- Some energy may have been transferred to electrons below the surface
,- Therefore for these electrons to liberate to the surface there will be heat transfer
through collision
- therefore the electrons leaves the surface will less than max
Energy Frequency equation Correct Answer E = hf
E = energy
h = plank's constant
f = frequency
Work function equation Correct Answer Work Function = h x threshold frequency
Work Function Correct Answer the minimum energy needed to liberate an electron from
a metal atom
Threshold Frequency Correct Answer minimum light frequency necessary to liberate an
electron from a given metal
Energy is proportional to frequency
Wave Particle Duality Model Answer Correct Answer
Nuclear Binding Energy Correct Answer The energy needed to separate a nucleus into
individual protons and neutrons
E = mc^2
Binding Energy = mass difference x the speed of light^2
How to calculate nuclear binding energy from a nuclear decay equation? Correct
Answer Th -> Ra + a
Mass of Th nuclear-(Mass of Ra nuclear + mass of alpha particle)
Convert u to kg
Multiply by speed of light^2 E = mc^2
Convert to Mev
How to convert u to kg Correct Answer kg / 1.6605x10^-27
How to convert kg to u Correct Answer kg / 1.6605x10^-27
What is 1 u? Correct Answer 1.6605x10^-27kg
, Converting u to Mev Correct Answer u x 931.5
Converting Mev to u Correct Answer Mev / 931.5
Electron Volt Correct Answer The energy given to an electron by accelerating it through
1 volt of electric potential difference. 1.6 x 10-19 joules.
Model answer for Fission Correct Answer - Strong nuclear forces that hold the nucleus
together only act a small distance
- When a big nucleus absorbs a neutron it deforms the nucleus
- The electrostatic repulsion between protons becomes greater than the strong nuclear
force
- it then splits (random)
Chain Reaction Correct Answer As a fission reaction splits it produces 3 neutrons which
can go on to split 3 other neutrons creating an exponential chain reaction
Model answer for fusion Correct Answer - two light nuclei join together to make a
heavier nucleus
- This gives out more energy per nucleon than than fission as the increase in binding
energy is much larger for fusion reactors
Advantages of Fusion over Fission Correct Answer - Power output is greater
- Raw materials are cheap and available (hydrogen in water)
- No radioactive waster is produced directly
Why Fusion is hard to do? Correct Answer The need for:
- enormous pressure
- enormous temperatures
We need these to get two nuclei close enough together to fuse
- Containment using magnetic fields uses more energy than the reaction yields
We need this because it is the only way to contain plasma from container walls
Binding energy per nucleon curve Correct Answer All reaction through fission or fusion
aim to get to iron 56 because it is the most stable element