3- Waves Flashcards
What are transverse waves?
Waves where the vibrations are at 90° to the direction of wave travel
What are longitudinal waves?
Waves where the vibrations are parallel to the direction of wave travel
What do all waves do?
Transfer energy but NOT matter
Can transverse waves move in a vacuum?
Some can
Can longitudinal waves move in a vacuum?
No
What can transverse waves move in?
Solids + liquids
What are examples of transverse waves?
- ripples on water
- X rays
- light
What are examples of longitudinal waves?
- sound waves
- ultrasound waves
- P- waves
What can longitudinal waves move in?
Solids, liquids + gases
What is amplitude?
The distance from the undisturbed position to the peak or trough of a wave
What is wavelength?
The distance from 1 point on the wave to the same point on the next wave
What is frequency ?
The number of waves passing a point in a second
What is the time period?
The time taken for a single wave to pass a point
Wavefronts close together = ?
Short wavelength
Wavefronts far apart = ?
Long wavelength
What is the Doppler effect ?
The apparent change In wavelength and frequency of a wave emitted by a moving source
What are Electromagnetic waves ?
Transverse waves that transfer energy from the source of the waves to an absorber
What are the properties of EM waves ?
- transverse
- can all travel through a vacuum at the same speed
- transfer energy
What are radio waves used for + why ?
Long range communication - can be reflected from the earth”s atmosphere
What are micro waves used for + why ?
Satellite communications + cooking - can penetrate earths atmosphere
What are infrared waves used for + why ?
Optical fibre communication- can undergo total internal reflection
What is visible light used for + why ?
Taking pics + vids- camera can detect visible light
What is ultraviolet used for ?
Detecting security ink
What are X-rays used for + why ?
To photograph bones- can penetrate soft tissues
What are gamma rays used for + why ?
To sterilise medical tools- gamma kills bacteria
Name everything in the EM spectrum from longest wavelength to shortest:
Radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, gamma rays
Why is radiation with higher energy harmful?
Highly ionising: harmful to cells + tissues causing cancer
higher frequency = ?
Higher energy of radiation
In the visible light spectrum, which colour has the longest + shortest wavelength?
Longest - red (lowest frequency)
Shortest- violet (highest frequency)
Increase in wavelength = ?
Decrease in frequency
Decrease in wavelength = ?
Increase in frequency
Shorter wavelength = ?
More ionising (dangerous)
What can sound undergo?
Reflection + refraction
What is reflection?
When a wave hits a boundary between 2 media + does not pass though but stays in the original medium
What is refraction ?
When a wave or light ray moves from one medium to another + its speed changes
From less dense material to more dense = ?
Light bends TOWARDS normal
From more dense material to less dense = ?
Light bends AWAY from the normal
More optically dense = ?
Higher refractive index
Less optically dense = ?
Lower refractive index
When does total internal reflection occur?
- when the angle of incidence is greater than the critical angle
- when the incident material is denser than the second material
What are the two uses for total internal reflection?
- Optical fibres
- periscopes
What is the critical angle
When the angle of refraction is exactly 90°
