Physics Topic 6 Flashcards
Waves t_______ e_____ from one place to another w______ transferring m_____..
Waves transfer energy from one place to another without transferring matter.
The wavelength of a wave is the…
… distance of one entire oscillation of that wave.
The amplitude of a wave is the…
… maximum displacement from the equilibrium position (the x-axis).
The time period is the…
… time it takes for one entire oscillation of a wave.
What is the unit for frequency?
Hz
What is the formula for frequency?
1/ time
A wave has a wavelength of 3 m and frequency of 20 Hz.
What is the wave’s speed?
3 x 20 = 60m/s
What is a transverse wave?
A wave where the oscillations are perpendicular to the direction of energy transfer.
What is a longitudinal wave?
A wave where the oscillations are parallel to the direction of energy transfer.
Waves are ________ reflected.
sometimes
Depending on the conditions, when light hits a material it can be (give 3):
Absorbed
Reflected
Transmitted
In reflection, the angle of incidence is always ________ the angle of reflection.
equal to
Give the 6 for reflection:
>\ | />
\ | /
_____!/____
Incoming ray
Point of incidence
Angle of incidence
Reflected ray
Normal
Angle of reflection
Specular reflection occurs on surfaces where the boundary is ____.
flat
What type of image will specular reflection produce?
A clear image
D______ reflection occurs on materials where the surface is bumpy (uneven).
Diffuse
Diffuse reflection means you ______ usually see your reflection in these materials.
cannot
Refraction refers to the change in _________ of a wave, as it passes from one medium to another, and is caused by its change in _____.
direction
speed
Does light travel slower or quicker in a more dense material?
slower
Light travelling from a less dense material, into a more dense material, will bend ________ the normal.
towards
Give the 7 for refraction:
Point of incidence
Refracted ray
Incident ray
Angle of incidence
Emergent ray
Angle of refraction
Normal
When a wave travels into a more dense medium, the wave speed decreases.
The frequency of the wave ______ ____ _____
stays the same
When a wave travels into a more dense medium, the wave speed decreases.
The wavelength of the wave _________
Decreases
In that cool light triangle…
What has happened to the different wavelengths of light contained within the white light?
They have all refracted at different angles
Electromagnetic waves are ____________ waves.
transverse
Transverse waves oscillate _____________ to the direction of energy transfer.
perpendicular
In a vacuum, electromagnetic waves travel at:
3 x 10 (to the power of 8) m/s
What is true of radio waves?
They have a long wavelength, and a low frequency
What is true of gamma waves?
They have a short wavelength, and a high frequency
Write the seven different regions of the electromagnetic spectrum in order of decreasing wavelength, starting with the longest.
Radio waves, microwaves, infrared red, visible light, ultra violet, x-rays, and gamma rays.
Which two of types of electromagnetic waves can be used in communication?
Microwaves
Radio waves
Give two types of electromagnetic waves are considered ionising:
X-rays
Gamma rays
Electromagnetic waves can be:
Transmitted
Absorbed
Reflected
True or false? Radio waves are electromagnetic waves with the longest wavelength and the lowest frequency
True
Radio waves can be created using an:
Alternating current
Oscilloscopes are used to:
Display the wave frequency of an alternating current
The three types of radio waves are:
Long Waves
Short waves
Very short waves
Which types of radio waves can travel long distances and diffract (bend) around the curved surface of the earth?
Long waves
What does a receiver do?
1) Absorbs the energy
2) Generates another alternating current which displays on another oscilloscope
Microwaves and infrared waves have ______ wavelengths than visible light.
longer
Some frequencies of microwaves can be absorbed by w____ molecules.
O____ frequencies of microwaves c_____ be absorbed by water molecules.
water
Other
cannot
Microwaves that can be absorbed by water molecules are used for:
Microwave ovens
Microwaves that cannot be absorbed by water molecules are used for:
Satellite communication
Infrared radiation is emitted from ___ objects that have thermal ____ energy.
all
heat
True or false? Higher temperature objects emit less infrared radiation than lower temperature objects.
False
Hotter objects emit more infrared radiation, as they have more energy.
Infrared cameras specialise in spotting live organisms because:
Infrared cameras can detect the infrared radiation emitted by animals
Animals are warmer than the surrounding environment and therefore emit more infrared radiation
Infrared r________ can be used to cook food and heat a room.
Both rely on h______ metal to a very high t__________.
The hot metal e____ a lot of infrared radiation.
radiation
heating
temperature
emits
Visible light is the spectrum of wavelengths that our eyes ____ detect.
can
Which type of electromagnetic waves have longer wavelengths?
Visible light
The acronym ROYGBIV can be used to remember the order of wavelengths in visible light, from longest to shortest wavelength.
Using the acronym, list those wavelengths in order below.
Red
Orange
Yellow
Green
Blue
Indigo
Violet
Which of the following is used to transmit data really quickly over very large distances (halfway around the earth)?
Short wave radio
Optical fibres
Planes
Optical fibres
While bouncing off the walls of optical fibres, all light rays must be totally reflected (rather than absorbed) at the same angle, so that the signal quality isn’t reduced.
Therefore, the reflection must be which type of reflection?
If all the light rays are all reflected at the same angle then it must be specular reflection. This is the same type of reflection you get from a mirror.
Ultraviolet light can be used to (give 2):
Check for ‘invisible markings’ on passports
Give sun tans
Destroy microorganisms in water sterilisation
Fluorescence is:
Ultraviolet light energy being absorbed and re-emitted as visible light
X-rays and gamma rays have the ________ wavelengths and _______ frequencies of all the electromagnetic waves.
shortest
highest
X-rays are used to view…
… the internal structure of objects.
How do X-rays work? Give 4 steps
1) X-rays are fired at the patient
2) X-rays are absorbed by materials which are very dense, like bones.
3) X-rays are transmitted through materials which are not very dense, like lungs and intestines.
4) The X-rays that pass through are detected by a detector plate to form an X-ray image
Over the long term, the risk of overexposure to X-rays is higher for:
Hospital staff administering X-rays.
Hospital staff normally leave the room when the x-rays are being taken, or wear protective clothing, so they only get very tiny doses per x-ray. However, because they are present for so many x-rays they normally end up receiving a greater dose than most patients overall.
In a hospital, gamma rays are used to:
Treat cancer
Perform medical imaging
G____ rays can be used to sterilise m______ equipment and food. The rays can kill m_____________ without causing any other damage.
Gamma
medical
microorganisms
True or false? X-rays and gamma rays cannot damage our cells.
False
Both X-rays and gamma rays are high energy radiation and can damage our cells, for example by causing mutations.
