Waves Test Revision Flashcards
What does a high refractive index do.
Bends the light more than a lower refractive index.
(R.I always > or = 1)
(always put air on top when calculating R.I)
What happens to the frequency and wavelength of light when it enters a material.
Frequency is not altered.
Wavelength decreases.
What happens to the velocity of a wave when it enters material.
Velocity is less in material.
Velocity decreases as density of the material increases.
How are the dark lines in the spectrum of sunlight produced?
Photons of certain frequencies are absorbed in the sun’s atmosphere.
Irradiance definition
Power per square meter.
When stating the relationship between Irradiance and distance…
Comment on whether Id² is CONSTANT or not, if constant the light is a point source.
Irradiance units
W/m²
How can you improve irradiance experiments?
Use a smaller lamp as it will be more like a point source.
Use black cloth on the bench to reduce reflections.
Why is a spectrum produced in a glass prism?
Different frequencies/ colours
have different refractive indices.
Why do angles to maxima/minima differ between colours.
Different colours of light have different wavelengths.
Since mλ = d sinθ, the angle will differ with different wavelengths.
What does it mean when waves are coherent?
The waves have a CONSTANT PHASE RELATIONSHIP and have the same frequency, wavelength, and velocity.
What can change the path difference.
Only changes in wavelength and order of maxima can alter the path difference since p.d=mλ.
Critical angle
n=1/sinθ
What happens when frequency incident on a metal plate is increased.
Maximum kinetic energy
of a photoelectron increases (since E=hf).
Number of photoelectrons
emitted per second decreases.
