{"id":138138,"date":"2022-04-11T10:30:12","date_gmt":"2022-04-11T05:00:12","guid":{"rendered":"https:\/\/www.aakash.ac.in\/blog\/?p=138138"},"modified":"2023-03-25T17:28:56","modified_gmt":"2023-03-25T11:58:56","slug":"what-is-the-refractive-index-cbse-class-10-physics","status":"publish","type":"post","link":"https:\/\/www.aakash.ac.in\/blog\/what-is-the-refractive-index-cbse-class-10-physics\/","title":{"rendered":"CBSE Class 10 Physics: What is the Refractive Index?"},"content":{"rendered":"

CBSE Class 10 Physics is a tricky subject like mathematics that many students fear. It is a blend of theoretical and practical concepts. Rather than developing a fear, the students should try to clarify the core concepts better. It will help them to understand the topics with ease and let go of their fear of physics from their mind. For this, a comprehensive and learning-oriented study material plays a significant role. We have high-quality study resources to help the students with efficient preparations for the final exams. Students will find our explanations very helpful to achieve success in the CBSE Class X boards. Our Class 10 <\/span>Physics Concepts<\/span><\/a> will also help students for <\/span>NTSE<\/span><\/a>, <\/span>Olympiad<\/span><\/a>, and other competitive exams. Today we will review one of the critical topics in physics, i.e., the Refractive Index. Now we will dive deeper to gain a good understanding of what is the Refractive Index?<\/span><\/p>\n

Get <\/span>NCERT Solutions for Class 11 Physics<\/span><\/a> and <\/span>NCERT Solutions for Class 12 Physics<\/span><\/a><\/p>\n

What is the Refractive Index?<\/h2>\n

Refractive Index measures the bending of a ray of light while it enters from one medium into another medium. In simpler words, The Refractive Index measures the change in speed of light when it passes into a medium from the air.<\/span><\/p>\n

The Refractive Index is also known as the Index of Refraction.<\/span><\/p>\n

The extent of change in speed of light in a medium depends upon the refractive index of that particular medium.\u00a0<\/span><\/p>\n

Fact Review<\/b><\/h4>\n

Refractive Index is the property that enables the construction of lenses, such as the lens used in cinema projectors, which focus the light to form real images.<\/span><\/p>\n

How to Calculate Refractive Index?<\/h2>\n

We have the formula to calculate the refractive index of a definite medium.<\/span><\/p>\n

Before jumping on to it, we must go through a short explanation regarding how the formula for refractive index is derived. Let us begin! In case you are looking for previous year\u2019s papers, access <\/span>Class 10 Previous Year Question Papers<\/span><\/a> here!<\/span><\/p>\n

Let us imagine a simple graph where a horizontal is a bifurcation mark for two mediums, medium I and medium II. You can further suppose medium I as vacuum and medium II as air\/water. Also, there is a vertical line perpendicular to the surface of the mediums. It is known as the Normal. Now, assume a ray of light passing from medium I to medium II. While entering into medium II, the ray of light will bend. The Refractive Index measures this change.\u00a0<\/span><\/p>\n

Putting light on the derivation,\u00a0<\/span><\/p>\n

Let i be the angle of incidence of a ray of light in a vacuum (medium I). It is the angle between the incoming light ray and the Normal line perpendicular to the surface. Then, r is the angle of refraction. It is the angle between the ray in medium II (air) and the normal.\u00a0<\/span><\/p>\n

Here, n symbolises the Refractive index. n is defined as the ratio of the sine of the angle of incidence to the sine of the angle of refraction. i.e.,<\/span><\/p>\n

\u00a0n = sin i \/ sin r<\/span><\/p>\n

Also, the Refractive index equals the velocity of light of a given wavelength in a space (c) divided by its velocity (v) in a substance. So, we can represent n as:<\/span><\/p>\n

Refractive Index = Velocity of light in vacuum\/ Velocity in a medium<\/span><\/p>\n

Or,<\/span><\/p>\n

\u200bThis implies that,<\/span><\/p>\n

\u00a0<\/span>n = c\/v<\/b><\/p>\n

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Some Common Refractive Indices<\/h2>\n

Different mediums have different Refractive Indices. The higher the refractive index of a medium, the slower is the speed of light. It causes a corresponding increased change in the direction of the light travelling within the medium.<\/span><\/p>\n

If the refractive index of a particular medium is 1.2, it means the speed of light in that medium is 1.2 times slower than the speed of light in a vacuum. The speed of light in glass is independent of the colour of light.<\/span><\/p>\n

Here are some common refractive indices for yellow light whose wavelength is equal to 589 nm, which are tabulated below:\u00a0<\/span><\/p>\n

Note: 1 nanometer = 10<\/span>-9<\/span> metre<\/span><\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n
Medium<\/b><\/td>\nRefractive Index<\/b><\/td>\n<\/tr>\n
Air<\/span><\/td>\n1.0029\u00a0<\/span><\/td>\n<\/tr>\n
Water<\/span><\/td>\n1.333<\/span><\/td>\n<\/tr>\n
Ice<\/span><\/td>\n1.31\u00a0<\/span><\/td>\n<\/tr>\n
Kerosene<\/span><\/td>\n1.44<\/span><\/td>\n<\/tr>\n
Ethanol<\/span><\/td>\n1.35<\/span><\/td>\n<\/tr>\n
Crown glass<\/span><\/td>\n1.517<\/span><\/td>\n<\/tr>\n
Dense flint glass<\/span><\/td>\n1.655<\/span><\/td>\n<\/tr>\n
Sodium chloride<\/span><\/td>\n1.54<\/span><\/td>\n<\/tr>\n
Diamond<\/span><\/td>\n2.417<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Fact Review<\/b><\/h4>\n

The medium having the highest refractive index of 2.417 is Diamond. It implies that the light-bending ability of diamond is approximately 2.42 times more than air.\u00a0<\/span><\/p>\n

Types of Refractive Index<\/h2>\n

Mainly there are two types of Refractive Index, i.e.,\u00a0<\/span><\/p>\n