P6: Waves Flashcards
what are the two types of waves
transverse and longitudinal
define a transverse wave
A wave for which the oscillations are perpendicular to the direction of wave transfer
what is a longitudinal wave?
a wave for which the oscillations are parallel to the direction of energy transfer
Give two examples of transverse waves
- Electromagnetic waves
- Seismic s-waves
Give two examples of longitudinal waves
- Sound waves
- Seismic p-waves
What are the two parts of a longitudinal wave called?
- compressions and rarefractions
Define amplitude
- the maximum displacement of a point on a wave away from its undisturbed position.
What is the definition of wavelength?
The wavelength of a wave is the distance from a point on one wave to the equivalent point on the adjacent wave.
What is the definition of frequency? Give the unit
The frequency of a wave is the number of waves passing a point each second.
- Hertz , Hz
What is wave speed?
The wave speed is the speed at which the energy is transferred (or the wave moves) through the medium
What does a wave transfer?
energy
State the equation used to calculate wave speed. Give appropriate units.
Wave speed = frequency x wavelength
speed = m/s
frequency = Hz
Wavelength = m
What happens to waves at the boundary between materials?
They can be reflected, absorbed or transmitted.
How do sound waves travel through a solid?
- the particles in the solid vibrate and transfer kinetic energy through the material
What is the frequency range of human hearing?
20 Hz - 20kHz
What are ultrasound waves?
- waves which have a frequency higher than the upper limit of human hearing
- (20kHz)
Give an example use for ultrasound waves
- medical or industrial imaging
What natural event causes seismic waves to be produced? What types are produced?
- Earthquakes
- They produce both P-waves and S-waves
State a difference between the mediums that P-waves and S-waves can travel through
- P waves travel through both solids and liquids
- S-waves only travel through solids
What technique is used to detect objects in deep water and measure water depth and how?
- Echo sounding
- high frequency sound waves are emitted, reflected and detected
- time difference between emission and detection alongside wave speed, are used to calculate distances
What type of spectrum do electromagnetic waves form?
A continuous spectrum
order the types of electromagnetic radiation from lowest to highest frequency
- radio waves
- microwaves
- infrared
- visible light
- ultraviolet
- X-rays
- Gamma rays
How do the speeds of EM radiation differ in a vacuum and in air?
- EM waves all travel at the same speed in a vacuum and in air
What property of waves in different mediums causes refraction?
- velocity
- wave speed is slower in denser materials, causing refraction
In which direction ( relative to the normal) do waves refract when entering a denser medium?
- they bend towards the normal
- the angle of refraction is less than the angle of incidence
What type of waves can be produced by oscillations in an electrical circuit?
- Radiowaves
How can radio waves create an alternating current in a circuit?
- When radio waves are absorbed , they can induce oscillations of electrons in a circuit
- with the same frequency as the radiowaves themselves
- causing alternating current
Where do gamma rays originate from ?
- they orginate from changes in the nuclei of atoms
give two health effects caused by ultraviolet waves
- they can cause the skin to age prematurely
- this can increase the risk of developing skin cancer
give two health effects caused by x-rays and gamma rays
- they are ionising radiation so can cause mutations in genes
- they can lead to increased risk of developing various cancers
Give three practical uses for infrared radiation
- electrical heaters
- cooking food
- infrared cameras