Waves And Radiation Flashcards
What’s the electromagnetic spectrum made up of?
Radio waves, microwaves, infrared, visible , ultraviolet, x-rays, gamma rays
Give 3 examples of waves
Water waves
Sound waves
Electromagnetic waves
What do waves in the electromagnetic spectrum do?
Transport energy
Define a transverse wave
In a transverse wave particles vibrate at 90degrees to direction of travel
Name four examples of transverse waves
Water waves, light waves, gamma rays and all members of electromagnetic spectrum
Define longitudinal waves
Particles vibrate parallel to the direction the wave travels in
Example of a longitudinal wave
Sound
How to we work out the speed of a wave?
Dividing the distance it travels by the time it takes to travel that distance
Do waves travel at different speeds in different materials?
Yes
Define the wavelength of a wave
Horizontal distance between two adjacent crests or troughs
Define amplitude
Half the height from top of crest to bottom of a trough
Define period of a wave
Time taken for one wave to pass a point
What is frequency?
Number of waves per second
In reflection what is a normal?
Line drawn at 90degrees to mirror surface
Where would you use a curved reflector?
Transmitters , receivers of waves eg sound
What is diffraction?
When a wave passes an obstacle it bends around the obstacle
Which wavelengths diffract more?
Long
If you have a narrow gap does diffraction occur more or less?
More
Electromagnetic waves are a combination of what?
Oscillating electric and magnetic waves
What is the speed of light?therefore what is the speed of a wave on electromagnetic spectrum?
3x10’8ms-1
Which end of the electromagnetic spectrum has a low frequency?
The bottom eg radio waves
Which end of the electromagnetic spectrum has the shortest wavelengths?
The top eg gamma rays
If an electromagnetic spectrum wave has a higher frequency the greater the..
Amount of energy associated with it eg gamma rays have more energy than radio waves
Define refraction
When light changes from one transparent material to another it changes speed
What is the speed of light in glass?
2x10’8ms-1
What is a critical angle?
When light travels from glass to air and the angle of refraction is 90degrees, then the angle of incidence in the glass is called the critical angle
Name 3 ways in which radiation can be detected
It blackens photographic film, passes through a Geiger muller tube and radiation causes scintillations
Name four natural and man made sources which background radiation come from
Radon gases from rocks and soil
Gamma rays from the ground
Carbon and potatpssium in the body
Cosmic rays
Name three examples of exposure to man made radiation sources
Medical X-rays
Airplane flights
Nuclear industry
Define half life
The half life of a radio active source is the time it takes half of the unstable nuclei in the source to decay. Half life is also the time it takes for the activity of a source to fall by half
What are the four steps for measuring the half life of a radiative source?
- Measure background count rate
- Direct source at Geiger muller tube and measure the count rate at regular intervals
- Subtract background count rate from count rate
- Draw a graph of corrected count rate vs time
What are the three types of radiation
Alpha, beta, gamma
What are three ways to reduce exposure to radiation?
Shielding i.e. Lead aprons, distance and exposure i.e. Keep time exposed to a minimum
Give an advantage of nuclear power
Do not release co2
Give a disadvantage of nuclear power
Waste from reactions is radioactive which makes it problematic to store
Give 5 examples of using radiation
Radiotherapy, instrument sterilization, traders, industry, agriculture
What is nuclear fission.
A large nucleus is made to split into two smaller nuclei with the release of a number of neutrons energy
What is nuclear fusion?
Occurs when two small nuclei join together to make a larger nucleus. During this fusion reaction energy is released. Stars use a fusion reaction to release energy
What’s alpha particle?
Made of 2 protons and 2 neutrons
What’s beta particle
Very fast moving electron. For,Ed when a neutron in the nucleus changes into a proton and a electron
What’s gamma radiation?
High frequency, high energy, electromagnetic radiation. Moves at the speed of light
What’s radiactivity?
Process ny which an unstable nucleus attempts to become stable by emoting radiation.
Which type of radiation is the most and least penetrating?
A is least. Y is most
