p4 waves

what is the direction of energy transfer in waves

the energy transfer is the way their traveling

what is amplitude in a wave

amplitude is the maximum displacement of a point on the wave compared to the undisturbed position

what is wavelength in a wave

the distance between the same point on 2 adjacent waves

what is frequency in a wave

the amount of times a complete wave completely passes a point in 1 second

what are longitudinal waves

a wave where the oscillations are parallel to the direction of travel, meaning the wave consists of compressions and rarefactions like sound waves

what are transverse waves

waves where the oscillations are perpendicular to the direction of energy transfer. waves like the EMF spectrum and ocean waves

formula for speed of a wave

wave speed(m/s) = wavelength(m) x frequency(Hz)

what is the law of reflection

the law of reflection states that the angle of incidence(i) is equal to the angle of refraction{r)

what is the normal

an imaginary line drawn perpendicular to the surface that is being reflected of

how would a demonstration of a ripple tank work

you set up a ripple tank with a barrier inside and watch to see the water get reflected

how does the virtual image appear after reflection

it appears as the same size, and the same distance away as the object from the mirror,

how do you draw the virtual image formed by a mirror.

first, you measure a normal and draw a virtual image. then you draw lines to link the eye to a single point on the virtual image. then where the lines cross the surface you draw lines to the same point on the real object

what are wavefronts

when multiple waves are moving together in the same direction, you make imaginary planes one wavelength apart to show the movement of a lot of waves in the same direction

what is refraction

when a wave crosses a boundary to another medium(or shallower water) it can change speed based on the density of the mediums, and of the boundary is at an angle the wave changes directions

how do you investigate refraction using water

in a ripple tank make the water shallower in one section by adding a block, and observe how the wave changes speed/direction when it comes over the block

how do you investigate refraction using light

you shine a beam at a transparent object and observe how the beam is refracted as it goes through it

what is the refractive index of an object

the refractive index is the ratio of the speed of light in a vacuum compared to in the material

what is the refractive index of air water and glass

air is 1.00 water is 1.33 and glass is 1.52 to 2 dp

how do you calculate the refractive index of an object

since the speed of light in air is almost the same as a vacuum, refractive index(n) = sin(angle of incidence in air(i)) / sin(angle of refraction in medium(r)) - n = sin i / sin r

what is internal reflection

when a ray tries to leave a material and go into air some of that ray stays in the medium and is reflected, the reflected ray still follows the rule i = r

what is the critical angle of a material

the angle of incidence at which the angle of refraction would be equal to 90 degrees

what is total internal reflection

when the angle of incidence is grater than the critical angle there is no refracted ray and the entire beam in totally internally reflected

what happens to a beam when leaves the medium at and angle of incidence less than/exactly at/greater than the critical angle

when it is less than the ray is refracted based on the refractive index and a bit of the ray is internally reflected. when it is exactly the refracted ray is parallel to the boundary and there is a stronger internally reflected ray. when it is more then there is no refracted ray, all of the light in internally reflected

what is diffraction

is when waves spread out as they ‘bend around’ obstacles

how does wavelength affect diffraction

a general rule is that the bigger the wavelength the more the wave is diffracted. when going through a gap, when the gap is the same size as the wavelength it will be diffracted fully, diffraction decreasing a hole size goes up

what does a converging lens do

it brings parallel rays to a focus

what are the three rules for converging lenses

parallel rays will go towards the focal point once they hit the lens, rays going through the center of the lens will go straight, rays that go through the focal point come out parallel

what do diverging lenses do

they make parallel rays spread out

what are the properties of an image formed by converging lenses

the image is flipped, but it is a real image, formed on the opposite side of the lens and can be projected onto a screen

what are the properties of an image formed by diverging lenses

the image is virtual and on the same side of the lens and the rays don’t converge so the image cant be displayed on a screen. the image is diminished

what lenses are used for what seeing disorders

for people with short sightedness diverging lenses are used to allow them to focus on objects in the distance

what images are formed by converging lenses in terms of the focal point

objects further than 2F form diminished and flipped images, from F to 2F an enlarged flipped image, and closer than F the light wont converge and a virtual image is formed, upright and enlarged

what is the focal point

the point where parallel rays converge when going through a converging lens

how and what lenses do magnifying glasses use

they use converging lenses, where when an image is placed closer than F it becomes an enlarged virtual image

what are the 7 colors of light sorted by increasing wavelength

violet, indigo, blue, green, yellow, orange, red. white is a mixture of all the lights combined

what does a glass prism do to a beam of light

if the beam is not monochromatic(made up of one wavelengths) then the prism will disperse the light and allow you to see the spectrum of light inside

what are the 7 types of electromagnetic waves

radio waves, micro waves, infra red, visible light, ultraviolet, x rays, gamma rays

what are the 3 main uses for radio waves

astronomers use them in radio telescopes to determine composition and motion of objects in far away galaxies, they are used for radio and TV transmissions, used in RFID tags for identification

what are the 2 main uses for microwaves

microwaves are used in phones for wireless communication like wifi and bluetooth, and they are used at a higher intensity in microwaves to heat food.

what type of electromagnetic waves do satellites use

microwaves

what are the 2 types of satellites

low orbit satellites that orbit the earth at low altitudes (1000km) but quickly. geostationary satellites are thousands of kilometers high and rotate with the earths spin meaning they are constantly over the same spot relative to the eath

what types of satellites do satellite phones use

they use both geostationary and low orbit satellites to transmit microwaves to and from the satellites which then relay that data to on ground stations.

what types of satellites do satellite tv broadcasts use

they use geostationary satellites by pointing a satellite dish to a spot in the sky where they receive relayed data from a ground station via a geostationary satellite

how do infrared security systems work and why are they used

since infrared radiation is always emitted, unlike visible light, cameras observe the changes in infrared radiation levels in a room and if there are drastic spikes it determines that something emitting infrared radiation is there

how do electric space heaters work

they heat a metal wire using electricity which emits a lot of infrared radiation that gets absorbed by the surrounding particles and gets transferred to their internal energy stores, making them hotter

2 ways infrared waves are used to transmit data

they can be used in stuff like remote controllers to transmit data over short distances with line of sight by using pulses, or they can be used in optical fibre since low wavelength infrared passes through glass meaning it can be used to transmit data through optical fibre

what are the 2 way sound signals can be transmitted

they can be transmitted as analogue(AM and FM radio waves) or as digital(through wires and in devices)

what are the advantages(4) and disadvantages(1) of digital compared to analogue transmission

digital signals can be sent amplified and therefore sent over greater distances, regenerating the signal is also more accurate on digital signals since it only has a certain bit depth, digital transmission allows for computers to interpret the sound, digital signals are transmitted faster, but sound loses quality when it becomes a digital signal.

how does sound work

it is a wave of vibration that hits your eardrum and allows your brain to interpret it as sound

what are the peaks and troughs of sound waves called

compressions are the peaks of sound waves, areas with high compression. rarefactions are the throughs of sound waves and are areas of low density

how do sound wave speed vary per medium

the denser the medium the faster the sound travels, so they travel the slowest in gas and the fastest in solids.

what is the speed of sound in air

330-350 m/s in air, 1235 km/h is considered the speed of sound (mach 1)

how do frequency and amplitude affect how a sound sounds like

higher frequency means a high pitched sound and a high amplitude means a loud sound

how do echoes happen

when sound waves reflect of flat surfaces and bounce back to the source

what is ultrasound

sound over 20 kHz, one that humans cant hear since human ears can hear from 20Hz - 20kHz

what are 2 implication of sound waves, industrial/medical

they can be used to look inside the body, since ultrasound waves are partially reflected when crossing into a different medium, and when they are reconstructed by a computer then can be used to create an image of something inside the body, they can be used to detect cracks in materials since ultrasound would pass through a perfect material but would get reflected of any imperfections

how is echoing used in submarines

it is used in sonar that sends out pulses of sounds and base on how long they take to get back they can determine if there are how for away on object is from them