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light with matter, and light often behaves somewhat like a stream of particles. This confusion about the true nature of light continued for some years till a modern quantum theory of light emerged in which light is neither a ‘wave’ nor a ‘particle’ – the new theory reconciles the particle properties of light with the wave nature.
- Optics
- Wave Theory of Light
- Modern Quantum Theory of Light
- Electromagnetic Waves
- Source of Light
- Types of Medium
- Ray
- Beam of Light
- Convergent Pencil of Light
- Parallel Pencil of Light
It is the branch of physics that deals with the study of light. It is mainly divided into three parts: 1. Geometrical optics or optics: Geometrical optics, or ray optics, describes light propagation in terms of “rays”. 2. Wave or physical optics:It is concerned with nature of light and deals with interference, diffraction and polarization. Wave mot...
According to the wave theory, light consists of electromagnetic waves. The light waves travel with a very high speed of 3 × 10 8 m/s in vacuum. The wavelength of visible light waves lies between 4 × 10 – 7 m to 8 × 10 – 7 m. The phenomenon of diffraction (bending of light around the corners of tiny objects) interference and polarization of light ca...
Quantum theory tells us that both light and matter consist of tiny particles which have wave-like properties associated with them. Light is composed of particles called photons, and matteris composed of particles called electrons, protons, neutrons. It's only when the mass of a particle gets small enough that its wave like properties show up. To he...
Light, microwaves, x-rays, and TV and radio transmissions are all kinds of electromagnetic waves. They are all the same kind of wavy disturbance that repeats itself over a distance called the wavelength. The waves which do not require a material medium for their propagation are known as electromagnetic waves. e.g. All light waves are electromagneti...
A body that emits light in all directions is said to be the source of light. The source can be a point source one or an extended one. The sources of light are of two types: 1. Luminous source: Any object that by itself emits light is called as a luminous source. e.g. Sun and Stars (natural Luminous sources), Electric lamps, Candles and Lanterns (ar...
When light falls on a medium, it can be treated in three ways. A medium is a substance through which light propagates or tries to do so. Based on this interaction mediums are classified into three categories. 1. Transparent: The medium which allows most of the light to pass through it is called a transparent medium. e.g. Air, Water, Glass etc. 2. T...
A ray of light is the straight line path along which the light travels. It is represented by an arrow head on a straight line . The direction of the arrow gives the direction of propagation of light.Imagining light as a ray makes it easy to describe, with great accuracy, three well-known phenomena: reflection, refraction and scattering. Let's take ...
A light beam or beam of light is a directional projection of light energy radiating from a light source.Sunlight forms a light beam(a sunbeam) when filtered through media such as clouds,foliage, or windows. A group of parallel rays is called a beam of light. It is also called a pencil of light. A pencil of light or a beam of light may be of three t...
Convergent Pencil is also known as convergent beam of light. In this case, as the beam of light progresses the rays converge to a point. Or A convergent Pencil is that in which rays of light propogate to meet at a particular point say O as shown in the figure. Convergent Pencil of light The diameter of the pencil goes on decreasing as the rays proc...
A parallel pencil is that in which all the rays move parallel to one another. The diameter of the pencil remains constant throughout as shown in figure 3. Parallel Pencil of light
Reflection of light: Each light obeys the law of reflection, which either stipulates that the angle of incidence equivalent to the angle of reflection. Refraction of light: It occurs whenever a light ray's velocity fluctuates even though it travels from one medium to another one. The index of refraction is a measurement of how much light refracts.
The refractive index of a medium is related to the speed of light. It is the ratio of the speed of light in vacuum to that in the given medium. For example, refractive index of glass is 3/2. This indicates that the ratio of the speed of light in glass to that in vacuum is 2 : 3 or the speed of light in glass is two-third of its speed in vacuum.
Fix a white sheet of paper on a drawing board or a table. Take a. comb and close all its openings except one in the middle. You can use a strip of black paper for this purpose. Hold the comb perpendicular to the sheet of paper. Throw light from a torch through the opening of the comb from one side (Fig. 16.1).
Chapter Wise CBSE Quick Revision Notes and Key Points for Class 9 Science Pdf free download was designed by expert teachers from latest edition of NCERT books to get good marks in board exams. NCERT Class 9 Science Notes contains physics, chemistry and biology notes of all chapters are part of Revision Notes for Class 9. Here we have given CBSE Class 9 Science Notes.
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Jan 18, 2024 · Class 9 Science NCERT Solutions is given here. Students can click on the links of the particular chapter for which they are finding the solutions. Chapter 1 Matter in Our Surroundings. Chapter 2 Is Matter Around Us Pure. Chapter 3 Atoms and Molecules. Chapter 4 Structure of the Atom. Chapter 5 The Fundamental Unit of Life.
