Waves Flashcards
Label the wave and describe what each part is.
The amplitude is from either the crest or the tough to the rest position. The wavelength is from crest to crest or trough to trough.
What is the difference between transverse and longitudinal waves? Give examples of both.
Transverse waves have vibrations that move perpendicular to the direction that the wave is moving. Two examples would be light waves and all other EM waves.
Longitudinal waves have vibrations that are parallel to the direction that the wave is moving. Two examples of these waves would be sound waves and shock waves.
What is the equation that links speed, frequency and wavelength? How do you use it?
You have to cover the letter that you are trying to find. You then use the figures that you have been given to calculate the value. For example, A radio wave has a frequency of 92.2 X 106 Hz and its speed is 3 X 108m/s. Find its wavelength.
- Rearange the formula. W = F X V
- Subsitute the numbers. W = 92.2 X 106 Hz divided by 3 X 108m/s
- Calculate. 3.25 m.
What is the law of reflection?
Angle of incidence = Angle of reflection
Where are the angles of incidence and reflection?
They are ALWAYS between the normal and the ray or the normal and the reflected ray. They are NEVER between the ray and the surface!!!!
What are the important points about drawring a ray diagram for an image in a plane mirror?
- The image is the same size as the object.
- It is as far behind the mirror as the object is in front.
- The image is virtual and upbright. The image is virtual because the object appeares to be behind the mirror.
- The image is laterally inverted- the left and right sides are swapped
What is diffraction? How does the gap that the waves are forced through affect how much the waves are diffracted?
Diffraction is waves spreading out.
What is refraction? What speeds up the wave? What slows down the wave?
Refraction is where a wave travells through a different medium that is either more or less dense and as a result it bends or changes direction. If the wave goes from a less dense medium to a more dense medium it is slowed down. If the wave goes from a more dense medium to a less dense medium it speeds up.
Learn the following diagram.
What is the electromagnetic spectrum? Do all EM waves travel at the same speed? List the parts in order starting with the longest wavelength to the shortest wavelength.
All parts of the electromagnetic spectrum travel at the same speed through a vacuum.
Fill in the gaps. EM waves with _____ frequencies have ________ wavelengths.
EM waves with HIGHER frequencies have SHORTER wavelengths.
What do we use radiowaves for?
We use long waves for radios because the waves are able to diffract around the curved surface of the earth, over hills, through tunnels and any other long distance places. Shorter wave radio signals can also be recieved at long distances from the transmitter because they are reflected from the ionosphere.
How are microwaves used for satellite communication?
Communication to and from satellites uses microwaves becuase you need to use microwaves that can easily pass through the earth’s atmosphere. The signal from a transmitter is transmitted in to space, where it is picked up by the satellite dish that is orbitting the earth. The satellite transmits the signal back to earth in a different direction where its recieved by a satellite dish on the ground.
Why do some scientists believe that mobile phones could have implications on your health?
Mobile phone calls also travel as microwaves between your phone and the nearest transmitter. Some wavelengths of microwaves are absorbed by water molecules and heat them up. If the water is in your cells, you might start to get health problems. There isnt any conclusive evidence either way at the minute.
How are infrared waves used?
- Remote controllers. Remote controls work by emmitting different patterns of infrared waves to send different commands to an appliance.
- Optical fibres. The signal is carried as pulses of light or infrared radiation and is reflected off the sides of a very narrow core from one end of the fibre to another.
