ApasScript.

Waves

These are Apas Cloud services: they run on our servers for a signed-in member. The examples below are shown already made; sign in to edit and run your own.

travellingWave Apas Cloud

A wave y = A sin(kx - ωt + φ) from its constants: the record `A`, `lambda` = 2π/k, `f` = ω/2π, `T`, `v` = ω/k, `k`, `omega`, `phase` (degrees). NCERT XI Ex 14.1.

waveFromLambda Apas Cloud

The same record from the amplitude, wavelength and frequency.

stringSpeed Apas Cloud

The speed of a transverse wave on a string, √(T/μ). NCERT XI Ex 14.2.

soundSpeed Apas Cloud

The speed of sound in a gas, √(γP/ρ) (Laplace); give gamma 1 for Newton's √(P/ρ). NCERT XI Ex 14.3.

soundSpeedAt Apas Cloud

The speed of sound from the molar mass and temperature, √(γRT/M).

soundSpeedScaled Apas Cloud

The speed at another temperature, v ∝ √T (kelvin).

bulkSpeed Apas Cloud

The speed of a longitudinal wave in a solid or liquid, √(Y/ρ) or √(B/ρ).

phaseDifference Apas Cloud

The phase difference in degrees for a path difference, 360 Δx/λ.

pathDifference Apas Cloud

The path difference for a phase difference in degrees, λ φ/360.

pressureAmplitude Apas Cloud

The pressure amplitude of a sound wave, ρ v ω s0.

soundIntensity Apas Cloud

The intensity of a sound wave, ½ ρ v ω² s0².

decibel Apas Cloud

The sound level, 10 log10(I/I0) with I0 = 1e-12 W/m².

intensityFromDecibel Apas Cloud

The intensity of a sound level in decibels.

superpose Apas Cloud

Two waves of one frequency with a phase difference φ: the record `A` = √(A1² + A2² + 2A1A2 cos φ) and `phase`, the resultant's lead on the first in degrees.

intensityExtremes Apas Cloud

Two waves of intensities I1 and I2: the record `max` = (√I1 + √I2)², `min` = (√I1 - √I2)², `ratio`.

amplitudeRatio Apas Cloud

The amplitude ratio A1/A2 from the ratio of the brightest to the darkest intensity, (√r + 1)/(√r - 1).

coherentIntensity Apas Cloud

The intensity of two coherent waves of I0 each with a phase difference φ in degrees, 4 I0 cos²(φ/2). NCERT XII Ex 10.3.

modeFrequency Apas Cloud

The frequency of the n-th mode: n v/2L for a string fixed at both ends or an open pipe, (2n - 1) v/4L for a pipe closed at one end. NCERT XI Ex 14.4.

modeWavelength Apas Cloud

The wavelength of the n-th mode: 2L/n, or 4L/(2n - 1) for a closed pipe.

modeOf Apas Cloud

The mode n whose frequency is f, or "none" when f is not a natural frequency (a closed pipe has no even harmonics).

nodePositions Apas Cloud

The positions of the displacement nodes of the n-th mode from the left end (a closed pipe's closed end), as a list.

antinodePositions Apas Cloud

The positions of the displacement antinodes of the n-th mode, as a list.

stringFrequency Apas Cloud

The n-th harmonic of a stretched string, (n/2L) √(T/μ) (the sonometer).

resonanceTube Apas Cloud

The first two resonance lengths with a fork of frequency f: the record `v` = 2f(l2 - l1), `lambda`, `e` = (l2 - 3 l1)/2 the end correction.

resonanceLength Apas Cloud

The n-th resonance length of a tube, (2n - 1) v/4f - e.

beats Apas Cloud

Two notes together: the record `f` = |f1 - f2| beats per second, `T` the beat period, `mean` the tone heard.

unknownFork Apas Cloud

The two frequencies an unknown fork may have, beating n times a second with a known one: [known - n, known + n].

doppler Apas Cloud

The Doppler effect for sound: the record `f` = f (v + w + v_o)/(v + w - v_s), `lambda` in front of the source, `shift`. Speeds are positive towards the other party (the source towards the observer, the observer towards the source) and negative away; the wind blows from the source to the observer when positive. NCERT XI Ex 14.6.

dopplerEcho Apas Cloud

A source moving at v_s towards a wall and hearing its echo: the record `atWall` = f v/(v - v_s), `heard` = f (v + v_s)/(v - v_s), `beats` with its own note.

dopplerWavelengths Apas Cloud

The wavelengths in front of and behind a moving source: the record `ahead` = λ(1 - v_s/v), `behind` = λ(1 + v_s/v), `lambda`.

waveOn Apas Cloud

A travelling wave y = A sin(kx - ωt) on the diagram: the snapshot at t over 2.5 wavelengths with λ and A marked and the arrow v, the snapshot at t + dt dashed, a particle at x with its velocity arrow (v_p = -v ∂y/∂x). The picture has its own scale; the real values are in the labels and caption; the summary gives f, T, k, ω.

waveGraphsOn Apas Cloud

The two graphs of a wave side by side: y against x at t = 0 with λ marked, and y against t at the particle x0 with T marked.

longitudinalWaveOn Apas Cloud

A longitudinal wave: a row of particles bunched and spread over two wavelengths with C and R marked, the displacement graph s(x) and the pressure graph Δp(x) = -B ∂s/∂x beneath (a quarter wave ahead).

pulseOn Apas Cloud

A pulse on a string meeting a rigid end (reflected inverted, a phase change of π) or a free end (reflected upright): three rows, arriving, at the end with its image, going back.

standingWaveOn Apas Cloud

The n-th mode of a string fixed at both ends, a pipe closed at one end or an open pipe: the envelope, N and A marked at the formula's positions, the holder drawn; f_n in the caption when v is given. The word "pressure" draws the pressure picture of a pipe (nodes and antinodes swapped).

harmonicsOn Apas Cloud

The first modes stacked, each named (fundamental, third harmonic, ...) with its wavelength and, when v is given, its frequency: a closed pipe shows the odd harmonics only.

resonanceTubeOn Apas Cloud

The resonance tube at its first two resonances side by side: the water levels, the fork, the quarter-wave and three-quarter-wave loops, l1, l2 and e marked; v = 2f(l2 - l1) and e = (l2 - 3l1)/2 in the caption.

beatsOn Apas Cloud

Beats: the two waves and their sum with the dashed envelope 2A cos(π(f1 - f2)t), the beat period marked; best with frequencies a few hertz apart (NCERT Fig. 14.15 uses 11 and 9).

superpositionOn Apas Cloud

Two waves of one frequency with a phase difference and their sum over two wavelengths, the resultant amplitude marked: A = √(A1² + A2² + 2A1A2 cos φ), ε in the caption.

phasorOn Apas Cloud

Phasors tip to tail from the origin and the resultant: the list holds amplitude, phase (degrees), amplitude, phase, ... for each wave; A and ε in the caption.

dopplerOn Apas Cloud

The Doppler effect: the wavefronts emitted at each period by the moving source, bunched ahead, with λ' ahead and behind marked, the observer with its velocity; f' = f (v + v_o)/(v - v_s) in the caption. Speeds positive towards the other party.

dopplerEchoOn Apas Cloud

A source moving towards a wall and hearing its echo: the two shifts, f1 at the wall and f2 heard back, and the beats with its own note.