Waves Flashcards
How is colour related to differential transmission?
- A coloured filter (e.g. green)
- transmits light of that wavelength only (e.g. green)
- and absorbs all other wavelengths
Use of visible light?
Fibre-optics
What are the hazards from UV waves?
- Ageing of skin
- Ionisation in cells can lead to skin cancer
3 things all electromagnetic waves have in common
- transverse waves
- travel at same speed in a vacuum
- transfer energy from emitter to absorber
(HT) How does absorption + emission affect the temp of an object?
- If absorption is higher than emission, the object’s temp increases
(HT) Why can humans only hear a limited range of frequencies?
- The conversion of sound waves to vibrations only works over a limited frequency range
Which part of the EM spectrum has the shortest freq / highest wavelength
Gamma
How are:
- freq
- speed
- wavelength
affected when sound travels from one medium to another?
- Freq: remains constant
- speed: may change
- causing it’s wavelength to change
2 uses of gamma rays:
- Radiotherapy
- Sterilising medical equipment
3 uses of infrared waves:
- Night-vision cameras
- Remote controls
- Cooking
2 e.gs of EM waves
- transferring energy
- from emitter to absorber:
Energy is TRANSFERRED:
- from the sun (EMITTER)
- via visible light
- to the Earth (ABSORBER)
Energy is TRANSFERRED:
- from X-ray machine (EMITTER)
- via X-rays
- to bones + photographic plates (ABSORBERS)
Factors which affect freq of an EM wave (2)
- Type of charged particle oscillating
- Frequency of the oscillation
What is the amplitude of a wave?
- maximum displacement
- of a point on a wave
- from its undisturbed position
(HT) What 4 things can happen when a wave interacts with matter?
Absorption
transmission
reflection
refraction
(HT) What happens to wave fronts when a wave travels from a less dense to a more dense medium?
They get CLOSER together
What is wavelength?
The distance across one complete wave cycle
What is a hazard of X-rays and gamma rays
- Ionisation in cells can lead to cancer
(HT) Why can humans only hear a limited range of frequencies?
The conversion of sound waves to vibrations of solids only works over a limited frequency range.
