Table of Contents

## Which famous German scientist discovered the theory of relativity?

In his early days in Berlin, Einstein postulated that the correct interpretation of the special theory of relativity must also furnish a theory of gravitation and in 1916 he published his paper on the general theory of relativity.

## Who invented the theory of relativity?

Albert Einstein

## What is Albert Einstein famous for?

Albert Einstein is justly famous for devising his theory of relativity, which revolutionized our understanding of space, time, gravity, and the universe.

## What did Philipp Lenard discover?

Philipp Lenard (1862-1947) was a German experimental physicist who advanced the study of X-ray tubes, the photoelectric effect and atomic theory. His results led him to propose (correctly) that most of the atom is composed of empty space.

## What is the Lenard effect?

(Also called spray electrification, waterfall effect.) The separation of electric charges accompanying the aerodynamic breakup of water drops, first studied systematically by the German physicist P. Lenard (1892).

## What is Lenard experiment?

It was in 1887 when Heinrich Hertz was conducting experiments to prove Maxwell’s electromagnetic theory of light, that he noticed a strange phenomenon. Hertz used a spark gap (two sharp electrodes placed at a small distance so that electric sparks can be generated) to detect the presence of electromagnetic waves.

## What is cut off or stopping potential?

Stopping potential or cut-off potential is defined as the required potential for stopping the removal of an electron from a metal surface when the incident light energy is greater than the work potential of the metal on which the incident light is focused.

## What was Hertz observation in his experiment?

The Hertz’s Observation: Heinrich Hertz in 1887 they observed that when light falls that too on a metal surface some electrons that are near the surface that absorb enough energy from the incident radiation to overcome the attraction of the positive ions in the material of the surface.

## What is the threshold frequency?

: the minimum frequency of radiation that will produce a photoelectric effect.

## What is the formula of threshold energy?

Kmin = Kth = −Q MX + mx MX This equation is valid if the energies are much less than rest mass energies of the involved particles. In other words, the kinetic energy and momentum of particles can be treated classically, or non-relativistic.

## What is the formula for stopping potential?

When the voltage equals the stopping potential, we know that the KE fo the ejected electrons just equals the potential energy at the collector or… KE = PE hf – φ = qV. This equation is very useful. For light shining on the metal, there is a minimum “cutoff” frequency before the ejected electrons have any KE.

## What is the difference between threshold frequency and frequency?

The energy and frequency of a photon are related by: The minimum energy required to produce photo-emission of electrons is called the work function this depends on the type of metal used. The minimum frequency of light required to give the work function energy is called the threshold frequency.

## Why is there a threshold frequency?

The threshold frequency of a metal refers to the frequency of light that will cause an electron to dislodge from that metal. Light at the threshold frequency will dislodge the electron with no kinetic energy. Light above the threshold frequency will eject an electron with some kinetic energy.

## What is the formula of threshold frequency?

At the limiting frequency called the ” threshold frequency “, the kinetic energy of the released electron is zero. Setting KE = 0 and replacing f by fth, we get: h fth = Wo or fth = Wo / h. The above formula gives the threshold frequency, fth .

## What is the symbol of threshold frequency?

electromagnetic phenomena The photoelectric threshold frequency, symbolized by the Greek letter nu with subscript zero, ν0, is that frequency at which the effect is barely possible; it is given by the ratio of the work function symbolized by the Greek letter psi, ψ, to Planck’s constant (ν0 =…

## What is the best description of threshold frequency?

What is the best description of ‘threshold frequency’? The minimum energy needed for electrons to escape a surface. The maximum kinetic energy that an emitted electron has. The minimum frequency of a photon that will cause an electron to be emitted.

## How do you calculate work function?

In mathematical terms, ϕ=hf−K, where ϕ is the work function and K is the kinetic energy of the electron. Thus the work function has been calculated without having to know the threshold frequency.

## What is Einstein photoelectric equation?

: an equation in physics giving the kinetic energy of a photoelectron emitted from a metal as a result of the absorption of a radiation quantum: Ek=hν−ω where Ek is the kinetic energy of the photoelectron, h is the Planck constant, ν is the frequency associated with the radiation quantum, and ω the work function of the …

## How did Einstein prove the photoelectric effect?

Light, Einstein said, is a beam of particles whose energies are related to their frequencies according to Planck’s formula. When that beam is directed at a metal, the photons collide with the atoms. If a photon’s frequency is sufficient to knock off an electron, the collision produces the photoelectric effect.

## What is the formula of photoelectric effect?

The Formula for Photoelectric Effect According to the famous Einstein explanation of the photoelectric effect: The energy of the photon will be sum total of energy needed to remove the electron and kinetic energy of the emitted electron. Thus h ν = W + E h \nu= W + E hν=W+E.

## Who found photoelectric effect?

Einstein’s

## Which metal is best for photoelectric effect?

cesium

## What is a quantum of light called?

Light quanta, called photons, are the smallest discrete amounts of light. For light quanta, we use the formula the energy of a photon = planck’s constant x frequency. So the way that we interpret is that the energy that’s present in electromagnetic waves is in these discreet packets called light quanta or photons.

## What is light made of?

Light is made of particles called photons, bundles of the electromagnetic field that carry a specific amount of energy. With sufficiently sensitive experiments, you can count photons or even perform measurements on a single one. Researchers have even frozen light temporarily.

## What type of waves are the longest?

Radio waves, infrared rays, visible light, ultraviolet rays, X-rays, and gamma rays are all types of electromagnetic radiation. Radio waves have the longest wavelength, and gamma rays have the shortest wavelength. Encyclopædia Britannica, Inc.

## Which color has the highest energy?

violet