Description of the Experience
This phenomenon was described by Albert Einstein whose name is associated with the theory of relativity. He got Nobel prize for explaining and description of photoelectric effect and Brownian motion but not for the theory of relativity which fundamentally channelled physical considerations in the 20th century and that after 300 years of Newtonian physics it was proved that his laws can be applied only in special cases when the body moves at a rate incomparably less than the speed of light in vacuum.
Einstein is one of the best known figures of 20th century physics, today we would say that he was a very famous celebrity whose photos were placed at first pages of newspapers. Even though only a few people understood his physics, mainly general theory of relativity, his eccentric personality and charisma caused that he attracted the attention of people.
He refused to wear socks, participate at formal social events and he liked to play violin. It is not true that he achieved bad results at school as it is often thought and the students then rely on it a think that even though they failed there is still a chance that they will be future Einstein. He was bored by the method of teaching because it was based on memorizing and he did not have any passion to Latin and Greek. Despite the fact that he left high school without finishing it he applied at a university and successfully finished it. It is not true that he was a religious person, he used the word god in his own way of meaning. He was a Jew and after Hitler took over the power his physics was not enough Aryan. He immigrated to the United States, to Princetown where he also died in 1955. He does not have a grave and his dust is scattered somewhere but we do not know the place because he did not want people to know it.
At the beginning of the 19th century it was known what the thermal emission is – that a metal heated to certain temperature emitted electrons but at the beginning of the 20th century it was discovered that metals are able to release electrons also without the high temperature. The will release them even if the radiation with a sufficiently high frequency hits them, so called cut-off frequency. Therefore it is enough to have a suitable radiation source, direct it to a metal sheet and its surface will release electrons which then move at certain speed, therefore they have kinetic energy.
h.f=W +0,5m.v.v Einstein’s equation of photoelectric effect
Product h.f is energy of the incident radiation which will be used to output work because electrons are bond in crystal structure of a metal and their kinetic energy they gain through their motion. The topic itself is not difficult and if the students want they will understand the phenomenon and the equation. The problem may be that energy on the left side of the equation is expressed in quantum mechanical way but I do not explain this to students because I do not have any resources from which I could gain that kind of knowledge.
Einstein could not find a job after finishing his studies but finally he was employed at Patent Office in Bern where he had enough time to think of the physics and where he wrote the theory of relativity which was later published in magazine Analen de Physik in 1905.
The students know who Einstein was and in the classroom we have his photo and cartoon.
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