Visible waves

The electromagnetic spectrum has a visible portion that will be visible to our human eye. Visible waves are light waves that are in the form of electromagnetic waves. In this article, we can come across the study material notes of visible waves, in-depth.

Visible waves

The visible waves or electromagnetic waves are the propagating waves that are formed by the fluctuation of electric and magnetic fields. Like other waves, light waves or electromagnetic waves can travel through matter or through vacant space.

Study material of visible waves

Speed of visible wave

The light waves travel through the empty space in about 300,000 km/s and travel slower in solids. The light from the sun travels 150 million km to Earth in about 8 ½ minutes.

Wavelength and frequency of light

The wavelength of light is expressed in nanometers(nm). We know that one nanometer is equal to 1 billionth of a metre. These waves have a narrow range of wavelengths about 700 to 400 billionths of a metre.

For example, the moonlight is actually the light reflected from the sun. These light waves travel through space and sky to reach our human eyes.

If the wave energy is higher, then the frequency of the wave will also be higher. Wavelength is inversely proportional to frequency. Shorter wavelengths have a higher frequency and longer wavelengths have a lower frequency.

Visible light and colour

As we already discussed, visible light waves have a narrow range of wavelengths from about 700 to 400 billionths of metres (nanometer). White light is the combination of different colours. The prism splits the white light to form different colours. The different wavelengths of light are bent at different amounts while changing the medium. Violet light has the shortest wavelength and is bent the most. Red light has the longest wavelength and bent the least.

Properties of visible waves

The three important properties of visible waves are reflection, refraction, absorption, and transmission through various materials.

• Reflection

Reflection is the property of the wave that can bounce back without absorption. When the wave hits the boundary, the direction of waves changes based on the angle at which they hit, called the law of reflection.

The law of reflection states that when the light wave hits a boundary at the angle, the reflective surface will be equal to the angle at which the wave leaves the surface. 

Here, we can see two types of reflection such as

• Diffuse reflection
• Spectacular reflection

Diffuse reflection happens on the rough reflective surfaces where the light gets scattered. Spectacular reflection happens on shiny surfaces where it reflects a mirror-like image.

Example

Transparent objects like glass, allow the light to pass through them. The opaque objects will not allow light to pass through them. The light passed through the opaque objects gets either absorbed or reflected.

• Refraction

Refraction is the important property that occurs when the wave passes from one medium to another. The wave speed gets changed. 

Example

Scientists use refracting telescopes which use lenses that work under the refractive property. Those refractive lenses are used to gather light from distant sources like stars, planets, etc., and focus the light through the human eye.

• Absorption

Absorption is the property in which the wave hits a boundary, and will get absorbed into the medium. It will neither get reflected nor refracted. When absorption occurs, heat is generated.

Example

When we wear a black dress, all the light waves get absorbed and we can feel the heat. When we wear a white dress, all the light waves get reflected and no heat can be felt.

• Diffraction property

Diffraction is the property in which the wave spreads out radially.

Example

The light bulb in the darkroom spreads out the light waves radially from the light bulb. Diffraction is also used in holographic images. These holographic images can be used in security measures on ID cards and credit cards.

• Intensity of waves

The amount of energy that a wave can carry is called wave intensity. It determines the brightness of the light. The dim light has lower intensity as the wave carries less energy. As the distance is away from the light source, the wave energy spreads out and the intensity of the wave decreases.

Applications of visible waves

The visible waves are used in most of the fields like

• Fibre optic communications
• Laser essential for product manufacturing
• Oxygen monitoring in the brain
• Radiation measurement
• Multifunctionality sensors in smartphones
• In semiconductor diodes
• Atmospheric observation by the laser beam.
• Early detection of cancer and dementia

Conclusion

Electromagnetic waves are transverse waves that consist of vibrating electric and magnetic fields. The electromagnetic spectrum has different waves like radio waves, infrared waves, visible light, and gamma rays. Of these, we have seen the study material notes of visible waves. Light waves are electromagnetic waves, which can be used to study illumination and photo theory in physics.