4.4 | waves

what is a progressive wave?

a wave that moves energy through space or a medium without moving the medium itself

what are the two types of progressive waves?

they differ in the direction of oscillation relative to energy transfer

what is an example of transverse waves?

they include types of waves where motion is perpendicular to direction of travel

what characterises a longitudinal wave?

they show alternating regions of compression and rarefaction

what is displacement?

a measure of how far a point on a wave is from its rest position

what is amplitude?

the largest distance a point on the wave moves from its rest position

what is wavelength?

the length between two matching points on consecutive waves

what does the period of a wave represent?

the time it takes for one full cycle to pass a fixed point

what is frequency?

a count of how many complete wave cycles pass a point in a second

what is phase difference?

a comparison of how in-step two points on a wave are

what does it mean for particles to be in phase?

they move together in sync with no time offset

what is the phase difference when two particles are in antiphase?

they are half a cycle out of step

what is the relationship between period (T) and frequency (f)?

they are mathematical inverses of each other

state the wave equation relating wave speed, wavelength, and frequency,

v = f lambda

how can frequency be determined using an oscilloscope?

by using time measurements from the waveform display

what happens during reflection of a wave?

the wave changes direction after hitting a boundary

what remains unchanged during the reflection of a wave?

key properties like frequency and spacing stay the same

what is refraction?

it's the bending of a wave as it moves between different media

what is polarisation?

it describes how wave oscillations are oriented

what remains constant when a wave is refracted?

frequency

how do sound waves behave in denser materials compared to electromagnetic waves?

they respond oppositely in terms of speed

what happens to the wavelength of a wave during refraction?

it changes due to a speed difference

what occurs at the boundary between two media during refraction?

some of the wave continues and some reflects

what is diffraction?

when waves spread out after passing through a gap

how are the wavelength and frequency of a wave affected by diffraction?

they stay the same while the shape spreads

when does maximum diffraction occur?

when the gap size matches a specific wave property

what is polarisation?

a property of transverse waves that define what planes the oscillations are restricted to.

can longitudinal waves experience polarization?

they can't because of how they oscillate

what equipment can be used to demonstrate wave properties?

a lab setup involving water can show this

how is refraction demonstrated in a ripple tank?

by altering the tank to change how waves move

what technique is used to demonstrate polarization of visible light?

it uses a special kind of optical filter

what happens to light intensity when two polarizing filters are rotated by 90°?

it drops sharply due to blocked orientations

how can polarization of microwaves be demonstrated?

a setup using a transmitter

what orientation allows maximum signal reception of microwaves through a metal grille?

the position of the grille that lets most waves through

what happens to the signal received when the metal grille is rotated to horizontal?

the wave gets absorbed and barely passes through

how is the intensity of a progressive wave defined?

the power spread over a surface area

what is the relationship between intensity and distance from a point source?

inverse square law

how is the intensity of a wave related to its amplitude?

intensity = amplitude squared

what type of waves are electromagnetic waves?

transverse waves

what can electromagnetic waves do that other waves cannot?

they can move through empty space

what is the speed of electromagnetic waves in a vacuum?

3×10^8

what part of the electromagnetic spectrum does visible light occupy?

a small section within a much broader range

what happens to a ray of light when it enters a new medium at an angle?

it bends and may partially reflect

how is the refractive index (n) calculated?

n = c/v

what formula relates the angles of incidence and refraction at a boundary between two media?

n1 x sin(theta1) = n2 x sin(theta2)

what is total internal reflection?

it happens when light stays completely inside a material

what is the formula for calculating the critical angle (C)?

n = 1/sin(C)

what is the principle of superposition in wave theory?

the idea that overlapping waves combine their displacements

what is constructive interference?

when overlapping waves reinforce each other

what is destructive interference?

when overlapping waves cancel each other out

what defines coherent waves?

they maintain a constant phase difference

what happens during interference of two coherent waves?

they produce a pattern of highs and lows

how can superposition be investigated for sound waves?

by using multiple audio sources and measuring with a device

what is the young double-slit experiment used for?

it explores interference patterns in light

what type of light does the young double-slit experiment use?

a single-wavelength source

what is the significance of the angle of incidence in total internal reflection?

it determines whether reflection happens

what are the two conditions necessary for total internal reflection?

a material and angle requirement must both be met

what is the relationship between the refractive index and the speed of light in a medium?

as one increases

what does the resultant displacement depend on in the principle of superposition?

it varies based on how the waves align

what is the role of the normal in refraction?

it’s used as a baseline for measuring angles

what is the effect of a higher refractive index on light speed?

it slows the wave down

what is the outcome of maximum resultant displacement in coherent wave interference?

it occurs when the wave peaks align

what is the outcome of minimum resultant displacement in coherent wave interference?

it occurs when the wave peaks and troughs cancel

what creates alternating bright and dark fringes on a screen in a double-slit experiment?

interference of light waves from two sources

what is the distance between two adjacent maxima in a double-slit experiment denoted as?

it's a common variable for spacing

what does the variable 'd' represent in the equation for determining wavelength in a double-slit experiment?

it's the separation between the slits and the viewing screen

what is the formula used to determine the wavelength of light in a double-slit experiment?

it's a ratio involving spacing and fringe distance

what is a diffraction grating?

a tool with multiple slits for splitting light

how is the distance between slits in a diffraction grating typically expressed?

as a number per unit length

what does the variable 'n' represent in the context of diffraction gratings?

the number for each bright fringe beyond the center

what is the angle between the 0th and nth maxima denoted as?

it's the angle used in diffraction equations

what are stationary waves formed from?

they result from two identical waves moving in opposite directions

what are nodes and antinodes in stationary waves?

one type stays still

how far apart are two adjacent nodes in a stationary wave?

they’re separated by half of a wave cycle

what is the phase difference between two points on a stationary wave given by?

it depends on how many nodes lie between the points

do stationary waves transfer energy?

they do not carry energy from place to place

how can a stationary wave be produced in a stretched string?

by setting up opposing waves along the string

what happens to the initial wave produced in a stretched string setup?

it reflects and meets the original wave

what is the role of a microwave transmitter in producing stationary waves?

it sends out waves that reflect and overlap

how can stationary waves be produced with sound in an air-filled tube?

it requires adjusting tube length until a resonance forms

what is the pattern of nodes and antinodes in an open-open air column?

both ends show strong vibration

what is the pattern of nodes and antinodes in an open-closed air column?

one end vibrates while the other does not

what is the fundamental frequency of a stationary wave?

the lowest tone the system naturally supports

what is the first harmonic in the context of stationary waves?

it’s the pattern made at the base frequency

what happens to the vibration pattern as frequency increases in stationary waves?

more complex shapes emerge

what occurs at frequencies other than multiples of the fundamental frequency in stationary waves?

no stable standing patterns form