This graph shows allowed quantized energy levels in a hypothetical atom.

How many photons are emitted per second by a He-Ne laser that emits 3.0 mW of power at a wavelength of 632.8 nm?.

What is the frequency and wavelength of a photon whose energy is 4.0 x 10-19 J?.

If a moving electron is stopped by 1 V of electric potential, we say it has 1 electron-volt (or 1 eV) of kinetic energy.

The electron-volt is the most useful unit on the atomic level.

Which has more energy in its photons, a red laser or a green laser?.

Which has more energy in its photons, a very bright, powerful red laser or a small key-ring red laser?.

The energy of a photon is calculated from it the frequency of the light.

A particle of light is called a “photon”.Particle behavior is pronounced on a very small level, or at very high light energies.

It has energy and momentum, just like particles do.In addition to behaving as a wave, it also behaves like a particle. λ: wavelength (m) (distance from crest to crest).c: 3 x 108m/s (the speed of light in a vacuum).We will frequently use one equation from wave optics in quantum optics.When we study ray optics, we ignore the nature of light, and focus on how it behaves when it hits a boundary and reflects or refracts at that boundary.This means it travels in a straight line. We know from geometric optics that light behaves as a ray.Atoms can absorb and emit quanta of energy, but the energy intervals are very tiny, and not all energy levels are “allowed” for a given atom.Quantized energy can be thought of as existing in packets of energy of specific size.Quantized phenomena are discontinuous and discrete, and generally very small.Physics on a very small (e.g., atomic) scale is “quantized”.

Nuclear physics lectures ppt