Waves(p)(p1/2) Flashcards
Are waves sometimes, always or never reflected
Sometimes
What can happen to waves(3)
Reflected, absorbed and transmitted
What is the angle incident to the angle reflection
Always equal
What is speculation reflection
Occurs on flat surface, producing a clear image.
What is diffuse reflection?
Occurred on material with bumpy surface, meaning reflection is not so clear
What is a wave?
Transfers energy from one place to another
What is the wavelength?
The distance of the entire oscillation
What is a longitudinal wave
Oscillations that are parallel to direction of energy transfer(exp: sound waves, seismic waves)
What is a transverse wave?
Oscillations that are perpendicular to direction of energy transfer(exp: electromagnetic waves[light, radio, string])
What occurs at refraction of light waves?
They change direction as they pass from one medium to another
Why do waves travel at different speeds In different material?
They have different different densities
What does it mean when there’s higher density? (To waves)
The waves are slower
What happens to waves that travel at an angle to more dense areas?
Will align towards the normal. Called refracted ray
What happens when waves travel at an angle to less dense area?
They bend away from normal (emergency ray)
What happens to the waves when they pass through different medians?
The speed of the waves changes
What is the formula which includes wave speed, frequency and wavelength
Wave speed = frequency x wavelength
Frequency stays the same
Wavelength decreases
Speed increases
What are electromagnetic waves?
They are transverse and travel at different speeds.
What are the different electromagnetic waves?
Radio waves
Microwaves
Infra red waves
Visible light
Ultra violet
X-rays
Gamma rays
What are gamma rays made from?
Radioactive decay
What are ultraviolet’s made from?
From electrons dropping down energy levels
Where do InfrA red waves come from?
Bonds that hold molecules together vibrate
How fast do electromagnet travel?
3x10(8) m/s
What do radio waves have?
Long wavelengths and low frequencies
What are electromagnetic waves made from?
Oscillating electric and magnetic fields
What radio waves have long wavelengths and lower frequencies than visible light?
Radio waves
-microwaves
-infrared waves
How do you generate radiowaves?
Requires transmitter, oscilloscope, and receiver
-The transmitter is connected to the oscilloscope to see frequency of alternating current. Which can be then used to determine frequency of wave
-receiver absorbs energy from transmitter, generating an alternating current that is connected to oscilloscope, which produces same frequency as transmitter wavelength
How do you use radio waves for long communication?
-long waves: can travel huge distances by bending around the curved surface of the earth
-short waves: travel long distances by being reflected upon the ionosphere
How do you use radio waves for short communication?
-short waves: blue tooth between phones
-very shot waves directly receive waves from transmitter
What 2 types of methods can be used for microwaves?
- Absorbing water: this is done via microwaves heating the food by water molecules in the food absorbing microwaves that then transfer energy to neighbour molecules via conduction and convection.
- Not absorbed: passes through atmosphere and received by satellite, that is then transmitted to satélite dish
What are infrared waves?
They are emitted from all objects that have thermal energy. Where the more hotter and object is, the more infrared radiation emitted.
What can infrared radiation be used for?
-infrared cameras: make us spot living organisms
-cooking in ovens, emit lots of radiation that heat food by transferring heat energy
(Harmful in large quantities)
What are UV lights used for?
-sun beds to get a tan
-sterilising water
-security to write secret messages
What is fluorescence?
Ultraviolet light absorbed and remitted as visible light
(Used in fluorescent light, to generate ultraviolet and absorb phosphorus, environmentally friendly )
What is visible light used for?
Humans to see
-communication via optical fibres. That are fin plastic or glass fibres that transmit pulses of light long distances as light is reflected (specular) every time it hits the surface
(Transmits data very quickly)
What are X-rays used for?
-view internal structure of objects, fire X-rays through body, That is received by detector plate .
[This is possible due to bones absorbing X-rays for being dense and that they pass through parts in body mostly air (lungs and intestine) (partially through fleshy parts, heart)]
-can detect broken bones
Who are X-rays dangerous for?
-for staff , so where lead aprons
-and give small amount of radiation to patient
What are gamma rays used for?
-medical imaging
-treat cancer
-sterilising microorganisms whiteout any other damage made to rest of object(used in medical equipment and food)
-although it is ionising radiation that can damage our cells. This could cause Vance but can be use to treat disease and diagnose it
