Invisible Waves 9 Flashcards
What is a wave?
a transfer of energy that spreads through a medium from the disturbance location, usually as vibrations in the medium
What is a transverse wave?
a wave that consists of a disturbance occurring perpendicular to the equilibrium
What is a longitudinal wave?
A wave that consists of a disturbance occurring parallel to the equilibrium
What is a pulse wave?
A wave that is caused by a single disturbance
What is a periodic wave?
A wave that is caused by a continuous and repetitive disturbance
What is a period?
The duration of a single vibration
What is sound?
A longitudinal wave travelling through a medium which can be detected by the ear
What is pitch?
The frequency of a sound wave
What is an electromagnetic wave?
A wave consisting of a vibrating electric field which causes a vibrating magnetic field
What is light?
Electromagnetic waves that can be detected by the eye
What is diffuse reflection?
The reflection of light from a surface that scatters the incident rays
What is specular reflection?
The reflection of light from a surface so that the incident ray is reflected at the same angle
What is refraction?
The change in direction of a wave passing from one medium to another one where it travels at a different speed
What is this?
Diffuse reflection
What is this?
Specular reflection
What happens when a pulse wave is reflected?
It goes back and forth until it dies out
Describe longitudinal wave characteristics
- sounds
- parallel
- rarefactions & compressions
- needs medium
Describe transverse wave characteristics
- Electromagnetic radiation
- Light
- perpendicular
- troughs and peaks
- doesn’t need medium
Describe the equation triangle for velocity, wavelength, and frequency
V
λ | ƒ
Describe the equation triangle for velocity, wavelength, and time (period)
λ
V | t
What is frequency measured in?
Hertz (Hz)
What is velocity measured in?
m/s
What is wavelength measured in?
metres (m)
What is time measured in?
seconds (s)
The bigger the amplitude the…
louder something is
The higher the frequency the…
higher the pitch
What does the speed of sound depend on?
The medium it’s going through
Does sound travel faster through air or a solid?
solid
What is ultrasound?
sound above 20,000Hz
Describe sound in terms of particles
When something vibrates, it hits the particles next to it causing them to vibrate, which then cause the particles next to them to vibrate, and so on until it dies out.
Order electromagnetic radiation from highest to lowest frequency
gamma rays, X-rays, ultraviolet, visible light, infrared, microwaves, radio waves
What does the visible spectrum wavelength range from?
700nm (red) to 400nm (violet)
Describe the characteristics of AM radio signals
- can get static
- vary amplitude based on message being sent
- frequency stays the same
- long wavelength
- can bend
Describe the characteristics of FM radio signals
- can’t get static
- vary frequency based on message being sent
- amplitude stays the same
- short (3m) wavelength
- can’t bend
What is this?
total internal reflection
When does total internal reflection happen?
When the angle of incidence is bigger than the critical ange
What is the critical angle?
The angle of incidence when the angle of refraction is at 90 degrees
How do you see colour?
objects absorb all visible light except they reflect the colour that they are back into your eye
What is the equation triangle for speed, time and distance
d
s | t
What is this?
Virtual image
What is this?
Real image
What is the difference between a real and virtual image?
Real images
- can be projected onto a screen
- distance between image and lens is always closer than the lens and the object
Virtual Image:
- Cannot be projected onto a screen
