Threshold Frequency: In case of emission of photoelectrons there is a minimum frequency which is called the threshold frequency. It is the minimum frequency of radiation that will produce a photoelectric effect. It is defined as the minimum frequency of incident light which can cause photoelectric emission i.e. this frequency is just able to eject electrons without giving them additional energy.
In electronics, the threshold frequency is cutoff frequency, and it is the frequency of the output signal power when the output signal power of the circuit (eg, wire, amplifier, electronic filter) exceeds or drops below the conduction frequency.
It was shown in experiments that;
- the frequency of the light needed to reach an exacting least value (depending on the metal) for photoelectrons to start evasion the metal,
- the maximum kinetic energy of the photoelectrons depended on the frequency of the light not the intensity of the light.