3.3 Waves Flashcards
Amplitude
Max displacement of oscillating particle from equilibrium position
Antinode
Fixed point on stationary wave where amplitude is maximum
Coherent
Constant phase difference and same frequency
Critical angle
The angle of incidence of a light ray must exceed this angle for total internal reflection to occur
Cycle
Interval for an oscillating particle from a certain displacement and velocity to the next time the particle has identical displacement and velocity
first harmonic
pattern of stationary waves on a string when it oscillates at lowest possible frequency
frequency
number of cycles of a wave that pass a point per second
longitudinal waves
waves with particles that oscillate parallel to the direction of propagation of the wave
laser
produces coherent, parallel beam of monochromatic light
node
fixed point on a stationary wave where displacement is zero
path difference
difference in the distances from two coherent sources to an interference fringe
period
time for one complete cycle of a wave to pass a point
phase difference
the fraction of a cycle between the oscillations of 2 oscillating particles - measured in radians
plane-polarised waves
transverse waves that oscillate in one plane only
progressive waves
waves which travel through a substance or space if electromagnetic
refraction
change of direction of a wave when it crosses a boundary where its speed changes e.g new medium
refractive index
speed of light in free space
spectrometer
instrument used to measure light wavelengths very accurately
stationary waves
wave pattern with nodes and antinodes formed when 2 or more progressive waves of same frequency and amplitude pass through eachother
superposition
effect of 2 waves adding together when they meet
total internal reflection
light ray will totally internally reflect at boundary of 2 substances when boundary has new substance with lower refractive index and the angle of incidence is greater than the critical angle
transverse waves
wave where direction of oscillations of the particles of the waves are perpendicular to the direction of propagation of the wave
wavefronts
lines of constant phase
wavelength
least distance between 2 adjacent vibrating particles with the same displacement and velocity at the same moment in time
Young’s fringes
parallel bright and dark fringes observed when light from a narrow slit passes through 2 closely spaced slits
period
time for one complete cycle of a wave to pass a fixed point
resonant frequency
the frequency of an oscillating system in resonance
applications of polarisers
sunglasses lenses - reduce glare, camera lenses - reduce glare, 3D glasses lenses - improve picture quality
single slit diffraction pattern
large central maxima twice width of subsidiary minima, decreasing height of subsidiary minima
effect on diffraction pattern of slit width
larger slit width means narrower central maxima / subsidiary minima closer together
xray wavelength
1nm
optical fibre
thin, flexible transparent fibre used to carry light pulses from one end to another
modal dispersion
lengthening of a light pulse as it travels along optical fibre due to continual total internal reflection of waves meaning some rays travel longer distance than others in fibre
interference
formation of points of cancellation and reinforcement where two coherent waves pass through eachother
natural frequency
frequency of free oscillations of an oscillating system
