Twenty flashcards covering wave physics from first principles through to geometric and wave optics. Includes the wave equation, transverse and longitudinal waves, superposition and standing waves, the Doppler effect, the inverse-square law, refraction and Snel...
Twenty flashcards covering wave physics from first principles through to geometric and wave optics. Includes the wave equation, transverse and longitudinal waves, superposition and standing waves, the Doppler effect, the inverse-square law, refraction and Snell's law, total internal reflection, thin lenses, diffraction and polarisation. Formula-focused revision for GCSE, A-Level, AP Physics 1 and 2.
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A disturbance that transfers energy and momentum through a medium or space without any net transfer of matter.
In transverse waves the oscillation is perpendicular to the direction of energy transfer (light, water ripples). In longitudinal waves it is parallel (sound).
π£
=
π
π
v=fΞ» β wave speed equals frequency multiplied by wavelength.
f=1/T β frequency in hertz is the reciprocal of the period in seconds.
The maximum displacement from equilibrium. Intensity is proportional to amplitude squared, so amplitude governs loudness in sound and brightness in light.
When two or more waves meet at a point, the resultant displacement is the vector sum of the individual displacements.
Constructive occurs when waves meet in phase (path difference of
π
π
nΞ»), increasing amplitude. Destructive occurs when in antiphase (path difference of
(
π
+
1
2
)
π
(n+
2
1
β
)Ξ»), reducing it.
A wave formed by two identical waves travelling in opposite directions. Nodes are points of zero amplitude; antinodes are points of maximum amplitude.
π
1
=
π£
2
πΏ
f
1
β
=
2L
v
β
, where
πΏ
L is the string length. Harmonics occur at integer multiples
π
π
=
π
π
1
f
n
β
=nf
1
β
.
About 343 m sβ»ΒΉ. It increases with temperature and is far higher in liquids and solids than in gases.
The change in observed frequency when a source and observer move relative to one another β frequency rises on approach and falls on recession.
πΌ
=
π
4
π
π
2
I=
4Οr
2
P
β
β intensity from a point source is inversely proportional to the square of the distance.
The angle of incidence equals the angle of reflection, and the incident ray, reflected ray and normal all lie in the same plane.
π
1
sin
β‘
π
1
=
π
2
sin
β‘
π
2
n
1
β
sinΞΈ
1
β
=n
2
β
sinΞΈ
2
β
, where
π
n is the refractive index of each medium and angles are measured from the normal.
n=c/v β the ratio of the speed of light in a vacuum to its speed in the medium. It is always greater than or equal to 1.
When light travels from a denser to a less dense medium at an angle exceeding the critical angle
π
π
ΞΈ
c
β
, where
sin
β‘
π
π
=
π
2
/
π
1
sinΞΈ
c
β
=n
2
β
/n
1
β
.
1
π
=
1
π’
+
1
π£
f
1
β
=
u
1
β
+
v
1
β
and
π
=
β
π£
π’
m=β
u
v
β
, where
π
f is focal length,
π’
u object distance and
π£
v image distance.
dsinΞΈ=mΞ», where
π
d is slit separation and
π
m is the integer order of the fringe.
Restriction of oscillations to a single plane. Only transverse waves such as light can be polarised; longitudinal waves such as sound cannot.
Radio, microwave, infrared, visible light, ultraviolet, X-rays, gamma rays. All travel at
3.0
Γ
10
8
3.0Γ10
8
m sβ»ΒΉ in a vacuum.
