Physics Year 8 Flashcards
Density
The amount of molecules in an area
Transverse waves
Waves that move up and down at 90 degree angle
Light is a transverse wave
Longitudinal wave
Waves that move back and forth
Wavelength
The distance between each crest
Crest
The top of a wave
Trough
The bottom of the wave
Equibilibrium
The line in the middle when drawing a wave diagram
Amplitude
The distance between the equilibrium and the crest or the distance between the equilibrium and the trough
What happens to light when it hits an object
It either reflects, absorbed or passes through
Transparent
When light passes through without being distorted
Examples are water and glass
Translucent
When some light passes through objects. The rest is reflected.
Examples are fogged glass and jelly
Opaque
This material does not allow light to pass through. The material absorbs the light or reflects the light.
Examples are wood and bricks
Ray
How light travels in a straight line
Incident ray
Light ray that travels towards a shiny surface
Reflected ray
The ray that is reflected from the shiny surface
Normal
The dotted line used to help draw a ray diagram
90 degrees
Angle of incidence
The angle between the normal and ray of incidence
Angle of reflection
The angle between the normal and ray of reflection
Law of Reflection
The angle of incidence is equal to the angle of reflection
Plane mirrors
These are flat mirrors
The image in the mirror is not magnified ut creates a virtual image
Refraction
When light travels at different speeds in different mediums, the image through the substance looks disjointed. It is the bending of light rays and this occurs when light travels from one medium to another with different densities.
What happens when light rays travel into a denser medium
The ray bends towards the normal because it becomes slower due to the amount of particles.
What happens when a light ray travels into a medium that is less dense
It bends away from the normal and travels faster.
Refracted ray
The ray that passes through the new medium
Lowest possible refractive index
Vacuum of 1
A high refractive index
Diamonds of 2.42
Refractive Index
The number that measures the density of a material
Prism
A triangular object that bends light to form the colours of the rainbow. It is translucent.
Dispersion
Separation of white light according to the colours with different wavelength
