Waves And The Electromagnetic Spectrum T2 Flashcards
What happens when waves travel through a medium?
The particles of the medium vibrate and transfer energy and information between each other
What is the amplitude of a wave?
The amplitude of a wave is the displacement from the rest position
What is the wavelength?
The wavelength is the length of a full cycle of the wave
What is the frequency of a wave?
Frequency is the number of complete cycles of the wave passing a certain point per second. Frequency is measured in hertz. 1Hz is 1 wave per second
What is the period of a wave?
The period of a wave is the number of second needed to compete 1 cycle. Period = 1 / frequency
What are transverse waves?
In transverse waves, the vibrations are perpendicular to the direction the wave travels. Most waves are transverse
What are longitudinal waves?
In longitudinal waves, the vibrations are parallel to the direction the wave travels
How do you calculate wave speed?
Wave speed = frequency x wavelength
What happens when a wave is absorbed?
The wave transfers the energy to the materials energy stores. Often the energy is transferred to the thermal energy
What happens when a wave is transmitted?
The wave carries on traveling through the new material.
What happens when a wave is reflected?
This is where the incoming rays are neither absorbed or transmitted, but instead sent back
What happens in refraction?
Waves travel at different speeds in materials with different densities, so when a wave crosses a boundary between materials it changes speed, if the wave hits the boundary at an angle, this causes a change of direction - refraction
How are sound waves caused?
By vibrating objects. These vibrations passed through the surrounding medium as a series of compressions and refractions
How do you hear sound?
Sound waves that reach you eardrum cause it to vibrate, these vibrations are past on to tiny bones in you ear called ossiles, through semi circular canals, and to the cochlea. Te cochlea turn these vibrations into electrical signals to the brain
What is ultrasound?
Ultra sou d is sound with frequencies higher than 20000Hz
How can ultrasound be used?
Medical imaging. Ultrasound waves can pass through the body , but when they reach a boundary between 2 mediums, such as fluid in the womb and the foetus, some pf the wave is reflected and detected.
What is infrasound?
Infrasound is sound with frequencies lower than 20Hz
What are p-waves?
they are seismic waves. P-waves are longitudinal, they travel through solids and liquids, they are faster than s-waves
What are s-waves?
S-2aves are transverse and only travel through solids, they’re slower than p-waves
What is the law of reflection?
Angle of incidence = angle of reflection
What is specular reflection?
Specular reflection is when waves are reflected in one direction by a smooth surface. This means you get a clear reflection like a mirror
What is diffuse reflection?
Diffuse reflection occurs when waves are reflected in all directions by a rough surface
What is white light?
White light is a mixture of all the different colours of light which all have different wavelengths
What are opaque objects?
Opaque objects do not transmit light, they absorb some wavelengths of light but reflect others and so they are the colour they reflect
What are transparent and translucent materials?
Objects which transmit light, not all light that hits the surface is absorbed or reflected, some pass through
What is a converging lens?
A converging lens bulges outwards in the middle. It causes parallel rays of light to be together at the principle focus
What is a diverging lens?
A diverging lens caves inwards. It causes parallel rays of light to spread out
What type of waves are electromagnetic waves?
Electromagnetic waves are transverse waves, they all travel at the same speed in a vaccum
What is the wavelength of radio waves?
10^4
What happens when there is a higher frequency of an EM wave?
The more energy it transfers so the more dangerous it is
How does radiation affect the earth’s temperature?
During the day, lots of radiation is transferred to the earth from the sun, some of this is reflected, but most of it is absorbed, the radiation is reflected and absorbed by the atmosphere, clouds and the surface
What are radio waves primarily used for?
Radio waves are primarily used for communication and broadcasting
What are microwaves used for?
Communication and cooking
What is infrared radiation used for?
Infrared radiation is used to increase or monitor temperature, it can also transfer infomation
How does photography work?
Photographic film reacts to light to form an image, digital cameras contain image sensors, which detect visible light and generate an electrical signal
What is ultraviolet used for?
Security pens and long life lights
What are x rays used for?
X rays let us see inside things, they can be used to see the internal structure of objects
What are gamma rays used for?
They are used for sterilising things such as medical equipment - they kill microbes
