waves Flashcards
what is a wave?
a disturbance created in a medium which transfers energy and momentum from one point to another
energy transfers in the direction of wave propagation
particles of the medium oscillate, the wave propagates
there is no transfer of matter during wave propagation
classification of waves
based on requirement of a medium for wave propagation:
electromagnetic
mechanical
based on vibration of particles in a medium:
transverse
longitudinal
what is a transverse wave
T 🔄 ⊥
a wave in which oscillation of particles in the medium is ⊥ to the direction of wave propagation
what is a longitudinal wave
l+l=ll
a wave in which oscillation of particles in the medium is || to the direction of wave propagation
+ | = ||
frequency
number of waves per unit time
/s or Hz
↑ frequency ↓ wavelength
time period
time taken to complete one full oscillation
seconds
relationship between frequency and time period?
f = 1/T
mean/equilibrium position
it is the position of a particle where there is no wave motion/propagation/disturbance in the medium.
crest
maximum displacement of a particle from its mean position, in the +ve direction.
trough
maximum displacement of a particle from its mean position, in the -ve direction.
amplitude
maximum displacement of a particle from its mean position, in the +ve or -ve direction.
compression
the region in a longitudinal wave where the particles are close to each other.
in area of compression, density and pressure ar higher than the normal values.
rarefaction
the region in a longitudinal wave where the particles are farther away from each other.
in area of rarefaction, density and pressure are lower than the normal values.
wavelength
distance between two consecutive crests/troughs // compressions/rarefactions.
wave velocity
wavelength/time period
time period = 1/f
so wave velocity = wavelength*frequency
v = λ * f
reflection
phenomena exhibited by a wave in which a wave bounces back into the same medium after being incident on a reflecting surface.
laws of reflection
the incident ray, the reflected ray, and the normal to the reflecting surface at the point of incidence, all lie on the same plane.
the angle of incidence is always equal to the angle of reflection.
refraction
phenomena exhibited by a wave in which a wave changes the direction of motion when it travels from one medium to another.
frequency remains constant during refraction. wavelength changes.
laws of refraction
the incident ray, the refracted ray, and the normal to the surface of separation at the point of incidence, all lie on the same plane.
ratio of sine of angle of incidence and sine of angle of refraction for a given pair of media is always a constant and is called the refractive index
conditions for tir
- incident ray should travel from denser to rarer medium
- angle of incidence should be > critical angle
critical angle = angle of incidence for which the corresponding angle of refraction is 90.
electromagnetic spectrum
radio
micro
infra(red)
visible
ultra
x
gamma
diffraction
phenomena in which a wave spreads whenever it comes across an obstacle or a slit, provided that the size of the obstacle or slit is comparable to the wavelength of the wave
dispersion
phenomena in which polychromatic light splits into its monochromatic constituents.
- this occurs due to refraction (use law 2 of refraction to prove)
