P6 Waves Flashcards
Waves
A way for energy to be transferred without transferring matter
How do waves transfer energy?
- The medium the waves travel through oscillate and transfer energy between each other, but overall stay in the same place
- Waves transfer energy in the direction they are travelling
Amplitude
The maximum displacement of a point on the wave from its undisturbed position
Wavelength
The distance from the same point on the two adjacent waves (usually the peak)
Frequency
The number of completed waves passing a certain point per second
Hz
Measures frequency
Transverse waves
- Oscillations are perpendicular to the direction of transfer energy
- All electromagnetic waves
- Ripples and waves in water
- A wave on a string
Longitudinal waves
Parallel to the direction of energy transfer
Wave speed eq =
Frequency * wavelength
What is used to measure the speed of sound?
Oscilloscope
What are the 3 things that can happen a wave meets a boundary between 2 materials?
- The wave is absorbed by the second material and transfers the wave energy to the material’s energy stores
- The wave is transmitted through the second material and the wave carries on travelling through the new material which often leads to refraction
- The wave is reflected, where it is not absorbed or transmitted. This is how echoes are created
What determines what happens to a wave at boundaries?
The wavelength and the properties of the material
Electromagnetic waves are what type of waves?
Transverse waves
Electromagnetic waves transfer energy from a … to an …
source (emitter), absorber
EM waves travel at …
the same speed through air or a vacuum (as they are vibrations of electric and magnetic fields)
Radio waves wl
1m - 10^4 m
Micro waves wl
10^-2 m
Infra red wl
10^-5 m
Visible light wl
10^-7 m
Ultra violet wl
10^-8 m
X rays wl
10^-10 m
Gamma rays wl
10^-15 m
Refraction
The change in direction at a boundary
What happens to the speed if a wave travels along the normal?
It will change speed but not refracted
What happens if a wave hits the boundary at an angle?
It refracts
What happens if the wave bends towards the normal
It slows down and if it bends away from the normal it speeds up
Optical density
Measures how quickly light can travel through it (the higher the optical density, the slower light waves travels through it)
Rays
Straight lines that are perpendicular to wave fonts and show the direction a wave is travelling in
Wave front
A line showing all of the points on a wave that are in the same position sa each other after a given number of wavelengths
What affects how much a wave is refracted by?
The density of 2 materials
Radio waves sources
- Radio
- TV
- Satellites
- Control
- RFID tags
Radio waves effects on the body
• Travel through body without doing harm or being observed
Radio waves main use and how it works
- Radio waves carry signals between your phone nearest phone mast
- This is done by alternating the current in an electrical current
Microwaves sources
- Mobile Phones
- Oven
- Microwave
- Grill
- TV transmitters
Microwave effects on the body
• Heat caused by microwaves can damage cells if exposed for a certain amount of time
Microwaves main use and how they work
- Main use is in microwaves
- They do this by penetrating into the food a few cm
- Water molecules absorb them casuing water to heat up
- Water cooks food
Infrared radiation sources
- Thermal cameras
- Night cameras
- TV Remote
- Optical Fibres
- Cooking and Heating
Infrared radiation effects on the body
• Infrared can be reflected off skin/
absorbed but if exposed for long then it can cause problems
Infrared radiation main use and how it works
- Infra red cameras capture IR rays that are coming towards it
- They are then turned into an electrical signal
- Displayed on screen
Visible light sources
- Normal cameras
- Photography
- Vision
- Photosynthesis
- Solar Power systems
- Fibre Optic Communication
Visible light effects on the body
• A lot of light can concentrate heat and therefore damage cells if exposed for a long time
Visible light main use and how it works
- Optical fibre cables are used with light
- It is entered through one way
- Reflected many times untill the end
- Allows for faster wifi
Ultraviolet sources
- Sun tan beds
- Security markers
- Flourescent lamps
- Detecting forged bank notes
- Disenfecting water
Ultraviolet effects on the body
• UV is dangerous because the waves are frequent enough to ionise the cells leading to mutations or cancer
Ultraviolet main use and how it works
- Security pens can be used with UV
- UV radiation is absorved and visible light is then emmitted
- This can also be used in money
Xrays sources
- Medical X-rays
- Exploring inner structure
- Airport Security Scanners
- Killing Cancer Cells
Xrays effects on the body
• Similar to UV waves so it can cause damage to cells eventually leading to cancer or mutations
Xrays main use and how it works
- Xrays are used for obviously “xrays”
- They pass straight through objects if they aren’t too dense or thick
- They stop and reflect at more dense things and produce am image
Gamma rays sources
- Radiation
- Nuclear bombs
- Sterilising food
- Sterilising equipment
- Killing cancer cells
Gamma rays effects on the body
• Gamma rays are dangerous because they can kill cells as they carry the most energy per second
Gamma rays main use
• Treating cancer
What is the measurement of harm from the body being exposed to radiation?
Sieverts
