Waves and the electromagnetic spectrum (topic 4-5) Flashcards
What is a longitudinal wave?
A wave that pass on energy by making particles vibrate. it consists of compressions where particles are pushed together and rarefactions were particles are spread out. e.g sound. The wave motion is parallel to the wave direction.
What the type of wave is the one that consists of crests and troughs.
A transverse wave. don’t require particles. e.g s waves or light. The wave vibrations are perpendicular to the direction of the wave.
What is the frequency of a wave? (Hz)
The number of times it passes a point in one second.
What is a wave period?
The length of time it takes for a wave to pass a point.
What is the amplitude of a wave?
The max distance of a point on a wave away from its rest position.
What is dispersion?
When light separates out into its colours due to their different frequency’s.
How to work out wave speed.
Frequency x wavelength
What is significant about radiowaves?
They are the longest wave with the least amount of energy.
What is significant about gamma rays?
They have the smallest wave with the most amount of energy.
What are the uses of ultra violet?
used in sewage work, disinfecting water and in fluorescent materials.
What are the uses of x-rays?
medical- examining bones, security to detect certain materials and shapes.
What are the uses of gamma rays?
Kills cancerous cells, sterilises equipment and kills bacteria.
What is an interface?
The boundary between two medias (different density’s)
What is the normal?
A line that is perpendicular to the interface.
What happens to a wave as it enters a medium with different density.
Speeds up(less dense): bend away from the normal slows down(more dense): bends towards the normal
What are seismic waves?
s waves and p waves
They are used to see the structure of the earth.
p waves can trave through both solids and liquids.
s waves can only travel through solids.
When does the angle of incidence become the critical angle?
At 90 degrees.
What is the law of reflection?
The angle of reflection is equal to he angle of incidence
what are the hazards of electromagnetic radiation?
- microwaves cause internal heating of body tissues
- infrared radiation is felt as heat and causes skin burns
- X-rays damage cells, causing mutations (which may lead to cancer) and cell death
- gamma rays also damage cells, causing mutations (which may lead to cancer) and cell death.