Photons And Electrons Flashcards
Frequency:
The number of complete waves that pass a point per second. Frequency is measured in hertz (Hz).
Wavelength:
The distance between two consecutive points on a wave that are in phase. Wavelength is measured in metres.
The photoelectric effect:
The process that occurs when light shines on a metal and electrons are ejected.
Significance of the photoelectric effect:
It establishes the quantum theory and it illustrates the particle nature of light.
A photon:
The quantum of energy when the energy is in the form of electromagnetic radiation.
Threshold frequency (f0):
The minimum frequency of incident radiation at which electrons will be emitted from a particular metal.
Work function of a metal (W0):
The minimum amount of energy needed to emit an electron from the surface of a metal.
Red shift:
A shift in the spectra of distant galaxies toward longer wavelengths, i.e. towards the red end of the spectrum.
An absorption spectrum:
Produced when white light from a source passes through a “cool” gas. It is also referred to as a line absorption spectrum.
An emission spectrum:
Produced when electrons “fall” from an orbital of higher energy to an orbital of lower energy. It is also referred to as a line emission spectrum.
