Physics Theory Flashcards
What are longitudinal waves?
When the vibrations move in the same direction as the energy travels in e.g. sound waves
What are transverse waves?
When the vibrations move at right angles to the direction the energy travels in e.g. visible light, EM spectrum
Do long wavelengths or short wavelengths diffract more?
Long wavelengths diffract (bend) more than short wavelengths
Do waves diffract more through a narrow gap or wider gap?
Waves diffract more through a narrow gap
List the waves of the EM spectrum in order?
Gamma rays, X-rays, Ultraviolet, Visible Light, Infrared, Microwaves, Radiowaves
What do all the waves in the EM Spectrum have in common?
-Travel at the speed of light
-Can travel through a vacuum
-Can be reflected
-Can be refracted
-Can be diffracted
List the colours of the visible spectrum from highest wavelength to lowest
red. orange, yellow, green, blue, indigo, violet
(ROYGBIV)
Define the particles in an atom
Proton: postive, mass=1, located in the nucleus
Electron: negative, mass= near 0, orbits the nucleus
Neutron: charge is 0, mass=1, located at the nucleus
Define Ionisation
The process of adding or removing electrons
Define Ionising Radiation
Materials that can cause ionisation in other atoms
Define the radiation type ‘Alpha’
Symbol: α
It is a Helium nucleus
Highly ionising
Absorbed by air or paper
Positive Charge
Large mass
Define the radiation type ‘Beta’
Symbol: β
It is a fast electron
Less ionising than alpha more than gamma
Absorbed by mms of aluminium
Negative Charge
Very small mass
Define the radiation type ‘Gamma’
Symbol: γ
It is a high energy wave in the Em Spectrum
Not very ionising
Absorbed by a few cms of lead
No mass or charge
What are the types of natural background radiation?
-Radan Gas
-Cosmic rays from the sun and outer space
-Rocks and Soil
-Foods (e.g. banana)
-The Human body
What are the types of artificial background radiation?
-Medical sources, e.g. x-rays
-Fall out from weapon testing
-Nuclear Power stations
-Radioactive waste
Describe the Half-Life Experiment
- To ensure a fair test measure the background radiation
- Use a geiger muller tube to count the number of decays from a source in a minute. Take away from the background radiation count
- Calculate activity over the minute (A=N/t)
- Repeat process at regular intervals
- Plot activity (y-axis) against time (x-axis)
- Use graph to find half life
What does the risk of biological harm from exposure to radiation depend on?
-The Absorbed dose
-The type of radiation (alpha, beta, gamma)
-The body/organs/tissue exposed
Define Nuclear Fission
The splitting of a large and unstable nuclei, into 2 more stable nuclei, neutrons whilst energy is released
Define a chain reaction during Nuclear Fission
When the neutrons produced by the fission reaction can then go on to further reactions
Define Nuclear Fusion
When 2 light nuclei combine to make a bigger nucleus, producing extra energy
Why is Nuclear Fusion mostly impossible on Earth?
-Fusion is how stars produce their energy
-It is difficult (close to impossible) to do on Earth for electricity production
-This is because fusion requires high temperatures and and abundance of light elements are required
What are the Pros of Nuclear Power?
-Clean: doesn’t produce CO2 and greenhouse gases
-Little fuel is required to produce a lot of energy
What are the cons of nuclear power?
-Non-renewable energy source
-A serious accident in a nuclear power station is a major disaster
-Nuclear power stations produce radioactive waste, some of which is very difficult to deal with
-After a few decades nuclear power stations themselves will have to be disposed of
What are the ways to keep safe around nuclear radiation?
-Use forceps to pick up source
-No contact with skin
-Protective clothing e.g. lead apron
-Limit time with source
-Point away from the body
