The distance between two successive crests and troughs of a wave is known as its wavelength. It’s one of the waveform’s most crucial properties. The sign denotes the wavelength (Lambda). The metre is the standard unit of wavelength measurement.There are 3 types of waves .

1. Mechanical
2. E.M 
3. Matter 

A wave is a depiction of energy transfer in a vacuum or across a material.

When energy moves through a medium, certain interruptions in the flow might occur, resulting in the development of waves.

The distance between the greatest amplitude displacement from equilibrium is defined as a wavelength as we already talked about.

The length of a wave might be short or lengthy. The Greek letter Lambda () is used to represent it.

Unit of wavelength-

Now we will talk more about the unit of wavelength, wave equation and how to measure visible light.

Unit of wavelength-

First we will talk about what we call a wave-

A wave is a depiction of energy transfer in a vacuum or across a material. When energy moves through a certain media (solid, liquid, or gas), the flow can be disrupted, resulting in waves.

 Some energies don’t require a medium to travel, hence they can travel in space. Light energy can move in a vacuum, however sound energy needs a medium to travel.

Types of wave-

Mechanical Waves: The transmission of mechanical waves requires the presence of a medium. All of Newton’s principles of motion apply to such waves. Water waves, for example, are mechanical waves since they require a medium to travel. In a vacuum, sound waves cannot travel. They need a way to go about it.

Electromagnetic Waves: Electromagnetic waves propagate without the use of a medium. They have the ability to travel in a vacuum. Magnetic and electric fields are connected to electromagnetic waves. X-rays, satellite systems, microwaves, mobile phones, radio, and other similar devices are examples.

Matter Waves: Matter waves are a concept that is abstract. Matter waves are made up of microscopic particles and are related with matter. They have to do with protons, electrons, neutrons, and other subatomic particles moving about. Atoms, the sun, the earth, and the moon, for example.

Lambda (λ) is a Greek symbol that represents the length of a wave. The metre is the SI unit for wavelength. 

Some other wavelength Units-

Wavelengths may be measured in a variety of ways.

The metre is the SI unit for wavelength.

The centimetre is the CGS unit of wavelength.

There are multiple and submultiple units in a wavelength.

Wavelength is measured in a variety of ways, including:

kilometre (km) 

millimetre (mm)

Terametre (Tm)

Gigametre (Gm)

The wavelength submultiple units are as follows: 

Decimetre is a unit of measurement (Dm)

Micrometres (mm) 

Unit wavelength equation-

Unit wavelength equation is the relation between wave velocity,wavelength and frequency of a wave

Equation= Wavelength = wave velocity/frequency

λ = vf

The wavelength, or distance between the crests in metres, is denoted by = λ

v = refers to the velocity of waves travelling in a certain direction in metres per second (m/s).

The frequency, or wave crests that pass over a place in a specific number of cycles per second or hertz (cycles/s or Hz), is denoted by the letter f.

Here the S.I unit of wavelength is m(metre).

How to measure visible light-

Photometer No. 1 

A photometer is a device that measures the intensity of light. A visible light metre is a device that measures visible light. 

There are two types of photometers: 

1. Luminance metres – determine a light source’s visual energy output.

For items like traffic lights and automotive tail lights, luminance measures are employed.

1. Illuminance metres: these devices measure the visual energy that falls on the surface of an item.

2. Sphere Integration 

“An integrating sphere receives electromagnetic radiation from a wholly external source, commonly for flux measurement or optical attenuation.” 

Fundamentals and Applications of the Sphere

3. A spectrometer is a device that measures the wavelengths of light. 

“A spectrometer’s primary job is to take in light, break it down into its spectrum components, digitise the signal as a function of wavelength, then read and display it on a computer.”

 Spectrometer 

4. Measurement of light 

A light metre is a gadget that measures the amount of light in a room. The amount of light measured in a plane is known as light level

Conclusion-

In this article we have learned about what is wavelength and different types of wavelength

Unit of wavelength and different methods to measure the visible light. When it comes to the power of light and light measurement, there are various terminologies and technologies that are employed. It’s crucial to comprehend how all of these disparate elements fit together.