Dual Nature of Matter and Light

The study of the various natures that a matter exhibits or possesses is what we call the theory of dual nature of matter. 

The theory of the dual nature of matter has been supported by numerous experiments which conclude that matter can either exhibit a wave nature or a particle nature. Lets learn more about this in detail below.

Dual Nature of Light Notes

The most important concepts of this dual nature of light are explained here. The properties of matter and light were initially described in terms of their particle nature. Corpuscular theory for light, for example, were few of the early steps that had an impact on arriving at this explanation. It was later discovered that matter has the properties a wave and therefore has a dual nature meaning it is both a particle and a wave.

This wave-particle dual nature in quantum mechanics is crucial because it shows that any particle or quantum entity can either be expressed as a wave or a particle. It helps to explain the behaviour of matter.

Photoelectric Effect

Photoelectricity is the expulsion of electrons from material surfaces. Material surfaces usually have both positive and negative ions. Some electrons on the surface of metal will absorb radiation from light and overcome their affinity with positive ions. They are able to release enough energy to travel out to the surrounding area. This is the essence of the photoelectric effect.

You should also be familiar with some related terms.

Threshold Frequency – The minimum frequency of incident radiation required to eject an electron from a metal surface.

Work Function – The minimum energy needed to expel an electron from its surface.

Threshold wavelength refers to the wavelength of light at which a photoelectron is ejected from a metal.

When Threshold Frequency is represented by f, Ɵ represents Work Function and Threshold Wavelength is represented by ƛ

Then,   Ɵ = hf =hc/ ƛ;

where h is Planck’s Constant. E=hf

Electronic Emission

It is the basic energy required for a metal surface to emit an electron. Any of these methods can supply it to the free electrons. below:

Thermionic emission: This is where thermal energy is provided to the electrons to free them from the metal by heating them up to make them jump out of it.

Photo-electric Emission: This is when light at a certain frequency is used to illuminate a metal surface. This process releases electrons. Photoelectrons are electrons which are photo-generated.

Field Emission: The electrons are subject to the electric field, which helps them emit electrons out of the metal.

Concepts Related to Photoelectric Effects 

The retarding or minimum negative potential is called the cut-off potential represented by V0. This is provided to a plate when photoelectric current is zero. It is also called  Stopping Potential.

Laws Of Photoelectric Effect

The laws of the Photoelectric effect are as follows:

• There is a minimum frequency, termed as Threshold frequency, under which no photo-electric emission occurs. 
• The kinetic energy of photoelectrons that are above its threshold frequency is always dependent on incident light frequency.
• The intensity of light is directly proportional to the photoelectric current. 
• Photoelectric emission can be termed a sudden process.
• The minimum negative potential when photoelectric current is zero is known as Stopping Potential (V0).