P6 - WAVES Flashcards
What do waves do?
Waves transfer energy without transferring matter.
What are longitudinal waves?
The direction of oscillation is parallel to the direction of energy transfer (e.g, sound)
-Consists of compressions and rarefractions.
What are transverse waves?
The direction of oscillation is perpendicular to the direction of energy transfer (e.g, water waves, Em waves, light)
What does a wavelength provide?
Provides a time period. (the time taken for one wave to pass)
How do you find the frequency?
1/time period
Order of the EM spectrum
Radio waves, Micro waves, Infra-red, Visible light, Ultra violet, X-rays, Gamma rays
Uses of the waves in EM spectrum
Radio- phones, tv, wifi
Micro- Cooking (water)
Infra-red -cooking (surface)
Visible- Vision
Ultra violet- Tanning (RISK OF SKIN CANCER)
X-rays - medical cans, security
Gamma rays - sterilising medical equipment
Describe the practical for EM spectrum
Show matte black is the best emitter and absorber of Infra-red; use leslie cube with infra-red thermometer.
Shows that shiny materials are the worst emitters and absorbers.
What is REFRACTION?
When waves enter a new material, their speed changes, as well as their angle.
In REFRACTION, if SPEED DECREASES..
Wavelength also does, while frequency stays constant.
In REFRACTION, if the WAVE SLOWS DOWN…
It bends towards the NORMAL; that means the angle of REFRACTION is SMALLER than the angle of INCIDENCE.
In REFRACTION, when the LIGHT EXITS..
It speeds up again, and it bends away from the NORMAL.
