Physics Light and Waves Topic- Key Knowledge Flashcards
What is a wave?
A vibration that transfers energy + information but not matter
What is a transverse wave?
The vibration is perpendicular to the direction of wave travel
What is a longitudinal wave?
Vibrations are parallel to the direction of wave travel
What is refraction?
The bending of light as it passes from one material to another, occurring due to the change in light speed
What is the critical angle?
The angle of incidence for which the angle of refraction is 90*
What is frequency?
The number of waves which pass a point per unit time (1s)
What is the law of reflection?
Angle of incidence = angle of reflection
What is the amplitude?
The maximum displacement of a point of a wave from its rest position (distance from centre to crest/trough)
What is wavelength?
The distance between a point on one wave and the same point on the next wave (e.g trough to trough)
Waves transfer —— and —— without transferring ——
Energy, information, matter
Use of radio waves
Broadcasting and communications
Use of microwaves, risk of microwaves
-Cooking and satellite transmissions
-internal heating of body tissue
Use of Infrared, risk of infrared
-Heaters and night vision equipment
-skin burns
Use of visible light
Optical fibres and photography
Use of ultraviolet, risk of uv
-Fluorescent lamps
-damage to surface cells, blindness
Use of X-rays
Observing the inner structure of objects and materials, including for medical applications
Use of gamma rays, risk of gamma rays
-Sterilizing food and medical equipment
-cancer, mutation
Give 2 uses of total internal reflection
-Periscope
-Endoscope
What is the wavefront?
An imaginary surface drawn to represent the vibrating part of a wave
What is the Doppler effect?
The change in a wave’s observed wavelength and frequency when there is relative motion between its source and an observer.
