Waves-Progressive waves and refraction Flashcards
What is a progressive wave ?
Wave with a net transfer of energy and a constant amplitude.
What is a stationary wave ?
Wave with no net transfer of energy and varying amplitude. ( made of 2 progressive waves with opposite propagation )
What is a mechanical wave ?
Oscillations of particles.
What is a electromagnetic wave ?
Oscillations of fields ( travel at c and are always transverse ).
What is a longitudinal wave ?
Wave where oscillations are parralel to transfer of energy.
What is a transverse wave ?
Oscillations are perpendicular to net transfer of energy( can be polarized ).
What is c ?
Speed if light in a vacuum ( 3x10^8 )
What is the amplitude of a wave ?
Its maximum displacement from the equilibrium position.
What is the frequency of a wave ?
Number of cycles per second at a fixed position.
What is the wavelength of a wave ?
Least distance between 2 particles that are in phase in a wave.
What is phase difference ?
Fraction of a cycle difference between two oscillating particles or waves.
What do displacement time graphs show ?
How one particle moves over time.
What does a distance displacement graph show ?
Displacement of particles at one moment in time.
What does 0 rad phase difference show ?
particles or waves being in phase.
How mangy degrees is πrad ?
180°
what is the formula for phase difference ?
Φ = Xx360/λ or Xx2π/λ
what do you call particles which are at oppositesof their cycles ?
in antiphase.
What is the EM spectrum ?
Radio waves
microwaves
infrared waves
visible light
ultraviolet
x-rays
gamma rays
What is the formula for frequency ?
f = 1/t
what is the formula for wave speed ?
C = Fλ
How does polarization work ?
A transverse wave is passed through a polaroid which has small slits that only lets waves in one plane pass through only.
What happens when a wave passes through 2 perpendicular polaroid’s ?
no transmission because at first no vertical plane is let through, secondly none of the horizontal plane can pass through therefore none of the wave can pass through.
What is refractive index ?
Ration between speed of light in a vacuum and speed of light in a medium.
Wat is the refractive index of a vacuum and air.
1
what is the formula for refractive index ?
n = c/speed of light in medium
What is snells law ?
n1sinθ = n2sinθ2
What is dispersion ?
Where different wavelengths of light refract by a different amounts.
What colors of light disperse the most and least ?
most - violet
least - red
What is the critical angle ?
angle at which the angle of refraction is 90°
what are the two conditions for total internal reflection ?
Ray travels from a high to low refractive index.
Angle of incidence is greater than the critical angle.
What is attenuation ? How can it be fixed ?
Impure glass causes light to lose their intensity.
Having a high purity glass.
What is modal dispersion ? How can it be fixed ?
Where the path is zigzag light and reflects a lot causes pulse broadening.
Making the fibre thinner.
What is spectral dispersion ? How can it be fixed ?
Where the light has multiple frequencies which have different refractive indexes which causes the light pulses to be split up.
Using a wave with only one single wavelength.
