Deck 5 = Physics Spring Term 2014 Flashcards
What is wave speed measured in?
-(m/s)
What is a wave?
-A wave is an oscillation along a medium.
What is a medium?
-A medium is the things that vibrates.
What are oscillation?
-Oscillations are another word for vibrations and convey the direction of energy transfer.
What is the frequency of the waves?
This is the number of waves passing through a any point per second.
What is the unit for frequency?
-Hz.
What is the time for one oscillation called?
-It is called a period.
What is the wave length?
-This is the distance between any point when the wave makes a full cycle, the line comes back to the same point.
What is the amplitude of a wave?
-This is the maximum distance a point moves from its rest position when a wave passes.
Examples of transverse waves?
-Light, surface water waves.
Examples of longitudinal waves?
-Sound waves, pressure waves, ultrasound.
What is wavelength measured in?
-(m).
What is amplitude measured in?
-(m).
What is the wave equation?
-speed = frequency x wavelength.
What is the law of reflection?
- i=r.
- angle of incidence = the angle of reflection.
Rules of electromagnetic waves?
-All are transverse, All travel at the speed of light in a vacuum
Speed of light in a vacuum?
-300’000km per second.
Define transverse wave?
-There oscillation are at right angles to the direction of travel. the waves transfer energy and a material gains energy when it absorbs them
Where do electromagnetic waves come from?
-They are emitted whenever charged particles oscillate or lose energy in some way.
What is the refractive index?
-In a vacuum, the speed of light is 300’000km/s, in air is nearly the same. However in glass it slows to 200’000km/s. refractive index = 300 000 / 200 000 = 1.5
Refractive index of light in a vacuum?
-1
What are the units of refractive index?
-None.
Low refractive index to high
-Speed decreases, Direction bends towards the normal, frequency stays the same, Wavelength decreases.
High refractive index to low
-Speed increases, direction bends towards the normal, frequency stays the same, wavelength increases.
Angles of incidence and reflection always…
-Touch a normal.
What is Snell’s law?
-Snell’s law can be used to calculate the refractive index of the glass block.
Equation for Snell’s law?
-N= sini/sinr n = refractive index.
The bigger the refractive index..?
-The slower the light will travel through the material.
Light entering semi-circular glass block?
-Diagrams show the same rules as normal refraction. Find the normal first. Light will bend towards the normal.
What is total internal reflection?(TIR)
-This is when the angle of incidence is greater than the critical angle. Both angles become equal.
What are uses of (TIR)?
-Cats eyes, light is reflected in prisms. Binoculars, lights is reflected in prisms like periscope. Windshield rain sensor, light beamed at the windscreen to see if there is rain drops, they will reflect if there are.
Experiment to determine the refractive index of glass?
-Look in book, or on sheet for info.
What is diffraction?
-Diffraction is when a wave bends around an obstacles to fill in the shadows behind it. Diffraction is only significant when wavelength is roughly the same as the obstacles size. (look at diagrams)
Finding the speed of sound in air?
-Look in book.
A use of ultrasound, range finding?
-Look in book.
A straight line on a Hooke’s law graph shows that?
Proportional Hooke’s law is being obeyed
Curved line on Hooke’s law graph shows that?
in proportional Hooke’s law disobeyed and the elastic band has been permanently streached
