Photon Definition
quantum energy in the form of electromagnetic radiation
Electron Volt definition
the energy gained by an electron when it is accelerated from rest in a vacuum through p.d. of 1 volt
Photoelectric emission Definition
is the release of electrons from the surface of a metal when electromagnetic radiation is incident on its surface.
It proves the particulate nature of light
What is the work function energy
Minimum energy required for an electron to escape from the surface
What are the 3 natures of NOT-light?
Electrons are emitted instantly
The maximum energy of an electron depends on their frequency.
The maximum energy of electron no depend on their intensity.
What proves the wave nature of matter?
Electron diffraction
De Broglie wavelength definition
is the wavelength that corresponds to the threshold frequency
Visible line emission spectrum using diffraction grating
dark bg with colored lines.
Visible line absorption spectrum using diffraction grating
colored bg with dark lines
What is the effect of Intensity increasing?
the rate of emission of photoelectrons to increase, since it increases photons per unit time.
Why does maximum kinetic energy of the electron not correlate with the intensity of incident radiation
frequency determines the energy of photon while intensity determines the number of photons per unit time. Kinetic energy of electron depends on energy of one photon.
State what is meant by threshold frequency
The minimum frequency of incident light required to cause emission of photoelectrons
State what is meant by threshold wavelength
The maximum wavelength of incident light required to cause emission of photoelectrons
Formation of emission line spectra
Electrons in a gas are “excited” to higher energy levels
These excited electrons then fall back to “ground state” energy levels.
As a result it releases a photon of light with an energy equal to the energy difference between the two levels and of specific wavelengths.
Formation of absorption line spectra
Or
White gas on cool gas shows a number of dark lines because
Photon absorbed by electrons excite electrons
photon energy equals to difference in energy levels
photon energy relates to a single wavelength
electron de-excites and emits a photon in any direction
