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CHEM 121 Studioby Learn4Less · UBC CHEM 121

CHEM 121 glossary

de Broglie wavelength

The wavelength of a moving particle with mass: λ=h/mv=h/p\lambda = h/mv = h/p. It is noticeable only for very light particles such as electrons; for everyday objects it is far too small to observe.

Wavelength and amplitudeA sine wave. The wavelength λ is the distance between two neighbouring crests; the amplitude is the height of a crest above the centre line.wavelength λamplitudefrequency ν: waves passing a point per secondc = λν

A moving particle behaves like a wave with λ=h/mv\lambda = h/mv.

Example

A neutron (1.675×10−271.675\times10^{-27} kg) moving at 2200 m/s has λ=6.626×10−34(1.675×10−27)(2200)=1.80×10−10\lambda = \dfrac{6.626\times10^{-34}}{(1.675\times10^{-27})(2200)} = 1.80\times10^{-10} m, close to atomic spacings, so crystals diffract neutrons.

See alsoWave–particle dualityMomentumPlanck's constantDiffraction