Flashcards in waves Deck (86)
what is a progressive wave?
a wave that carries energy from one place to another without transferring material.
How can you tell certain types of waves carry energy?
The source will lose energy. X-ray and gamma rays knock electrons out of their orbits, causing ionization.
What is the displacement of a wave?
How far a point on the wave has moved from its undisturbed position. Measured in meters.
What is the amplitude of a wave?
The maximum displacement.
What is the wavelength of a wave?
the length of one whole wave from crest to crest or from trough to trough. The shortest distance between 2 adjacent points in phase. Measured in meters.
What is the period of a wave?
The time taken for one whole vibration. Measured in seconds.
What is the frequency of a wave?
The no. of vibrations per second passing a given point. Measured in hertz.
What is the phase difference of a wave?
The amount which one wave lags behind another wave. Measured in degrees or radians.
The wave is bounced back when it hits a boundary.
What is refraction?
The wave changes direction as it enters a different medium. The change in direction is a result of the wave speeding up or slowing down.
How is the frequency of a wave found?
1 / period.
How can the speed of a wave be found?
speed= wavelength X frequency.
What is a transverse wave?
The vibrations are at right angles to the direction of travel.
What are the 2 ways transverse waves can be drawn on a graph?
Displacement against against distance along the path of the wave. Displacement against time.
What are longitudinal waves?
The vibrations are along the direction of travel. They consist of areas of compression and rarefaction in the medium they travel through.
What is a polarized wave?
A wave that only oscillates in one direction. It can only happen with transverse waves.
What does a polarizing filter do?
It will only let certain waves through that are at the right angle.
What would happen if you shone light through 2 polarizing filters at 90 to each other.
No light would get through.
How do em waves work?
They consist of vibrating electric and magnetic fields.
What is the order of the em spectrum?
radio, micro, infared, visible ultraviolet, x-rays gamma rays.
What is the relation to the energy of an em wave and where it comes from in the atom?
The greater the energy, the closer to the center of the atom it came. Gamma waves come from inside the nucleus, x-rays to visible light come from energy level transitions in atoms, Infared and microwave come from molecules. Radio waves come from oscillations in electric fields.
What is the optical density of a material?
The more optically dense a material is, the slower light will go when within it.
What is the absolute refractive index of a material?
The ratio of the speed of light in a vacuum and the speed of light in the material. Divide the speed of light by the speed of light in the material.
What is a relative refractive index?
The ratio between the speed of light in one material compared to another. Divide the speed of light in a vacuum by that of the material. It should be a number less than 1
What is the angle of incidence refraction?
The angle the incoming light makes will the normal and the angle the refracted light makes with the horizontal.
What happens when light goes from one material into another with a greater optical density?
It bends towards the normal.
What do you assume the speed of light in air to be?
The speed of light in a vacume.
What is the angle of refraction?
The angle the refracted Ray makes with the normal.
What does n mean?
The refractive index of a material.