P1 - Radiation and Waves Flashcards
what is a wave?
a disturbance that transfers energy without transferring matter
what are transverse waves?
the vibrations are at right angles to the direction of wave travel.
what are longitudinal waves?
the vibrations are parallel to the direction of wave travel.
what is the equation of wavespeed?
wavespeed (m/s) = frequency (Hz) x wavelength (m)
how can i measure frequency with a ripple tank?
1) float the cork in the ripple tank (it should bob up and down)
2) when the cork is at the top of a “bob”, start the stopwatch. time how long it takes for 10 bobs
3) divide by 10 to get the time for 1 bob, the period
4) calc using the formu frequency = 1 ÷ period
how can i measure wavelength with a ripple tank?
- place a card covered with cm squared paper behind the ripple tank
- turn on the strobe light until the waves appear to freeze
- using squared paper, measure the distance
what 3 things can happen when a wave meets a boundary between 2 materials?
absorbed
transmitted
reflected
define refraction
waves changing direction at a boundary
what must always change if the wave of the speed changes?
the wavelength
how can you investigate reflection using a ray box and a mirror?
- take a piece of paper and draw a line across it
- place a mirror lining up with the line
- use a ray box to shine a thin beam of white light to the mirror
- trace the incident and reflected ray
- measure the angle between the incident and normal ray
how can you investigate refraction of light using a prism?
- draw a solid line around the prism on paper
- shine laser beam to the prism at an angle
- trace the incident and emerging rays onto paper and remove prism
- draw the refracted ray by joining the ends of the other 2 rays with a straight line
short wavelength, high frequncy on EM spectrum?
GRUVIMR
long wavelength, low frequency and?
reverse GRUVIMR
what does it mean when electrons can be “excited” to high energy levels?
an electron can move up one or more energy levels in one go if it absorbs EM radiation with the right amount of energy
how is visible light, ultraviolet, and x-rays created?
when atoms lose energy by an electron dropping down an energy level and emitting energy in the form of EM radiation
list some examples of ionising radiation
- gamma rays
- high-energy ultraviolet
- x-rays
explain why exposure to gamma radiation can lead to cancer?
it’s ionising
which can lead to mutations of cells and their abnormal growth
how do optical fibres work?
by bouncing light off the sides of a very narrow core. the pulse of light enters a core at a certain angle at one end and is reflected again and again.
what can infrared cameras detect?
can detect IR radiation and monitor temperature. they detect the IR and turn it into and electrical signal, which is displayed on a screen as a picture.
use of x-rays
can be used to view the internal structures of objects and materials, including our bodies
uses of gamma rays
sterilisation of medical instruments
cancer treatments
uses of ultraviolet
UV lamps in tanning salons
fluorescent lights use UV radiation to emit visible light
the wavelength of radiation the object emits most of is called?
the principal wavelength
as the temperature of an object increases, the intensity of every emitted wavelength…
increases!!!
what happens to the temperature if the principal frequency increases?
the temperature increases
what happens with radiation when the object is hotter than it’s surroundings?
it emits more radiation that it absorbs, so over time, it cools down
what do greenhouse gases do? (2)
trap radiation in the Earth’s atmosphere, which allows the Earth to be warm enough to support life.
what is the greenhouse effect
greenhouse gases absorb a large amount of radiation by the Earth, then remit the radiation in all directions, including the Earth
what affects the amount of green house gases in the atmosphere
deforestation
burning fossil fuels
agriculture
what is the em spectrum made up of?
made up of oscillating electric and magnetic field
how can we generate the em spectrum?
using electricity in the form of an alternating current, as alternating currents are made up of oscillating charges
