Light class 10 notes

               𝕃𝕚𝕘𝕙𝕥 

➜ Introduction of Light:

● Light is a form of electromagnetic radiation that can be detected by the human eye.

● It travels in straight lines called rays and can undergo various phenomena such as reflection, refraction, and dispersion.

1). What is light? 

1.1 Electromagnetic Spectrum:

●Light is a form of electromagnetic radiation that consists of tiny particles called photons.

●The electromagnetic spectrum encompasses a wide range of wavelengths, including radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays.

●Visible light is the portion of the electromagnetic spectrum that can be detected by the human eye.

1.2 Properties of Light:

● Light travels in straight lines known as rays.

●It can be reflected, refracted, diffracted, and absorbed.

● Light exhibits dual nature, behaving as both particles (photons) and waves.

2). Reflection and Refraction:

2.1 Reflection:

● Reflection occurs when light encounters a surface and bounces back.

● The laws of reflection state that the angle of incidence (the angle between the incident ray and the normal) is equal to the angle of reflection (the angle between the reflected ray and the normal).

● Reflection can be categorized into regular reflection (producing a clear image) and diffuse reflection (producing a scattered image).

2.2 Refraction:

●Refraction is the bending of light when it passes from one medium to another of different optical density.

●The speed of light changes when it enters a new medium, causing the light ray to bend.

●The laws of refraction state that the incident ray, the refracted ray, and the normal to the surface at the point of incidence all lie in the same plane.

●The ratio of the sine of the angle of incidence to the sine of the angle of refraction is constant and is known as the refractive index.

Dispersion and Colors:

3.1 Dispersion:

● Dispersion refers to the splitting of white light into its constituent colors when passing through a prism or a medium with varying refractive index. 

● The phenomenon of dispersion demonstrates that different colors of light have different wavelengths and thus bend at different angles.

● The resulting spectrum of colors can be observed in rainbows and various optical devices.

3.2 Colors and Wavelengths:

● The visible spectrum comprises colors with different wavelengths.

● The order of colors in the spectrum is often remembered using the acronym ROYGBIV (Red, Orange, Yellow, Green, Blue, Indigo, Violet).

4). Optical Instruments:

4.1 Human Eye:

● The human eye is a remarkable optical instrument that enables vision.

● It consists of various components, including the cornea, lens, iris, and retina.

● The lens focuses light onto the retina, where the image is formed and transmitted to the brain via the optic nerve.

4.2 Other Optical Instruments:

● Microscopes utilize lenses to magnify small objects and reveal microscopic details.

● Telescopes collect and focus light from distant celestial objects, allowing us to observe them in greater detail.

● Cameras use lenses to focus light onto a photosensitive surface or sensor, capturing images and recording memories.

➜ Conclusion:

The chapter on light unravels the mysteries of this remarkable electromagnetic radiation. By studying the properties of light, including reflection, refraction, dispersion, and its role in optical instruments, we gain a deeper understanding of the world around us. Light's ability to reveal colors, form images, and enable vision highlights its significance in our lives and scientific endeavors. Exploring the principles of light broadens our knowledge and paves the way for advancements intechnology, communication, and our understanding of the universe. With each discovery and application, we come closer to harnessing the full potential of light and its myriad of possibilities.