# Hertz and Lenard’s observation

This observation is related to the photoelectric effect and how this effect is proven by two scientists one experiment was conducted in 1887 by Heinrich Hertz to prove electromagnetic theory of light when he observed strange phenomena as he placed two electrodes at small distance so that an electric spark can be generated and he used spark gap to apply this experiment so that he can observe the presence of electromagnetic waves. The same is the case with Lenard as he observed the kinetic energy of electrons emitted increased with the radiation used. Both of their experimental shows the different type of samples or experimental to prove the same thing but they all were given green signal only when this is confirmed and proven by Einstein.

## What are the experimental observation of photoelectric emission?

Every metal consist of certain minimum frequency of incident radiation below which no photoelectrons are emitted or are not able to emit this type of frequency is called threshold frequency in which the increasing frequency of the beam which is incident keep the number of photons fixed and this would keep proportionate increase in energy and also increase the kinetic energy to its maximum and this leads to stop voltage increase. It is also mentioned that if the intensity of the incident radiation is increased there will be no effect on the kinetic energy of photoelectrons as kinetic energy depends upon the frequency of light and the level of energy provided by each photon. On the other hand, stopping voltage doe not depends on the intensity of the light but can be provided the light frequency be fixed at a point.

## What is kinetic energy?

In physics, kinetic energy is the energy possess by a moving object or by its motion. In other words, it can be defined as work which needed a body to accelerate from it’s actual position to the position it wanted to reach and the body keeps this kinetic energy until and unless it changes it’s speed same goes with the case of accelerating of body from moving at a speed to diverting itself towards the rating part. It is said that energy occurred in many forms which include chemical energy, thermal energy, electromagnetic energy, nuclear energy and rest energy and many more can be added to this category. Kinetic energy is an energy that can be seen in a moving object and also in the resting one.