# refractive index class 10

The refraction of light takes place on going from one medium to another because the speed of light is different in two media. Medium in which speed of light is more is called. How to deviate light rays by 180 degrees with a prism? In figure 1 (a) you can see several rays of light parallel to the principal axis are falling on a convex lens. Question 2 What is the speed of light in vacuum? A ray of light going towards the center of curvature of convex mirror is reflected back along its own path. The amount of change in speed of light in a medium depend upon the property of medium(refractive index) Now the ray emerges or comes out of the slab along RS making $\angle SR{{N}_{4}}=e$ , called the angle of emergence. For drawing ray diagrams we first consider how light rays falling on both concave and convex lens in three different ways get refracted. A Spherical lens is a piece of transparent glass bound by two spherical surfaces. Refractive index of medium 2 wrt medium 1 is known as refractive index of medium 2. eval(ez_write_tag([[250,250],'physicsteacher_in-medrectangle-1','ezslot_8',145,'0','0']));report this adCopyright © 2020 PhysicsTeacher.in. Question 6 What happen When light goes from denser medium to rarer medium? Mirrors we use on our dressing tables in our home are plane mirrors. Numerical problems on the refractive index. It is denoted by the letter D. 1 diopter is the power of a lens whose focal length is 1 meter so, $$1D=1m^{–1}$$. Convex lens converges the light rays as shown below in the figure 1(a). Ray diagram helps us to study the nature, position and relative size of the image formed by lenses. The refractive index is written as RI as well. A ray PQ is incident on it an face AB at point Q, making an angle $PQN_1=i$, called angle of incidence. So the RI of water is:Solution: air µwater = C /V = speed of light in air / speed of light in water = ( 3 x 10^8) / (2.25 x 10^8) =1.33eval(ez_write_tag([[250,250],'physicsteacher_in-banner-1','ezslot_9',148,'0','0'])); 3 ] The RI of the diamond is 2.41. Gravitational Field Strength on the earth’s surface, Gravitational field strength formula and definition. It is represented by the letter C. Please note that the center of curvature is not a part of the mirror. Question 4 What is relative refractive index? Learn about Refraction of light and law of refraction | refractive index and how to calculate refractive index for Physics class 10. Wavelength of visible light waves is very small and is of the order of $$4 \times {10^{-7}}m$$ to $$8 \times {10^{ - 7}}m$$. This point is called the principal focus of the concave mirror. Experiments show that refraction of light occurs according to certain laws. Distances measured perpendicular to and below the principal axis (along -y-axis) are taken as negative. If we now observe the reflected rays we see that they are all intersecting at a point F on the principal axis of the mirror. All right reserved. A convex lens bulges outward and is thick at the center and thinner at the edges. Lakhmir Singh, Together with CBSE/NCERT Practice Material Chapterwise for Class 10 Science, Mastering Numericals and Objectives of Physics for Class X, On the same side of the lens as the object, Between infinity and optical center O of the lens, Light is a form of energy due to which we are able to see the objects which emits light for example objects like sun, However, it lies behind the mirror in case of a convex mirror as shown above in the figure 2. and this happens because they reflects lights which falls on them from a luminous object like sun, lamp etc. The nature, position and size of the image formed by a concave mirror depend on the position of the object in relation to points P, F and C. The image formed can be real as well as virtual depending on the positions of the object. It is represented by the letter P. The power P of a lens of focal length f is given by. In case of convex mirror rays get reflected at the reflecting surface of the mirror and these reflected rays appear to come from point F on the principle axis and this point F is called principle focus of convex mirror. The distances measured against the direction of incident light are taken as negative. 1)When light goes from rarer medium to denser medium. Image formation by a convex lens for different positions of the object is shown below in the table, Nature, position and relative size of the image formed by a concave lens for various positions of the object is given below in the table. The angle of incidence is equal to the angle of reflection, and. Secondly consider the case for concave lens, The ray diagrams for the image formation in a convex lens for a few positions of the object are summarized below in the table, The ray diagrams for the image formation in a concave lens for a few positions of the object are summarized below in the table. Filed Under: Class 10 , Light-Reflection and Refraction Tagged With: absolute refractive index , light goes from denser medium to rarer medium , light goes from rarer medium to denser medium , refractive index , relative refractive index , speed of light The distances measured upward and perpendicular to the principle axis are taken as positive. These rays, after refraction from the lens, are appearing to diverge from a point on the principal axis. The SI unit of power of a lens is ‘diopter’. DISCLOSURE: THIS PAGE MAY CONTAIN AFFILIATE LINKS, MEANING I GET A COMMISSION IF YOU DECIDE TO MAKE A PURCHASE THROUGH MY LINKS, AT NO COST TO YOU. Filed Under: Class 10, Light-Reflection and Refraction Tagged With: absolute refractive index, light goes from denser medium to rarer medium, light goes from rarer medium to denser medium, refractive index, relative refractive index, speed of light. It lies outside its reflecting surface. The distances measured downwards and perpendicular to principle axis is taken as negative. For understanding about principle focus and focus length of a spherical mirror first consider the figure given below. A concave lens will always give a virtual, erect and diminished image, irrespective of the position of the object. He is an avid Blogger who writes a couple of blogs of different niches. Angle of incidence and angle of emergence are equal as emergent ray and incident ray are parallel to each other. Letter F is usually used to represent principal focus. This point on the principal axis is called the principal focus of the concave lens. $$\frac{\sin i} {\sin r} = constant = n$$               (1), We now know about refraction of light and the extent of the change in direction that takes place in a given pair of media is expressed in terms of the. Collisions and Newton’s Laws of Motion – How to relate these? It is given by, If medium 1 is vacuum or air, then the refractive index of medium 2 is considered with respect to vacuum. light goes from denser medium to rarer medium, light goes from rarer medium to denser medium, Economics Chapter 1 Development – Notes & Study Material, Geography Chapter 6 Manufacturing Industries – Notes & Study Material, Geography Chapter 5 Mineral and Energy Resources – Notes & Study Material. How to calculate the time the earth takes to go around the sun, using Newton’s Universal Law of Gravitation? Concave mirrors are used as shaving mirrors, reflectors in car headlights, hand torch and table lamps. Nature, position and relative size of the image formed by a convex mirror is given below in the table. IGCSE Physics worksheets | GCSE Physics problems | Physics questions – worksheet. Principle axis: - Straight line passing through the pole and the center of curvature of a spherical mirror is called principle axis of the mirror. This implies that the light from the object falls on the mirror from the left-hand side. Thanks for visiting our website. A lens, whether it is a convex lens or a concave lens, has two spherical surfaces which form a part of a sphere. It means that incident ray and emergent ray makes equal angles with parallel normal ${{N}_{1}}Q{{N}_{2}}$ and ${{N}_{3}}R{{N}_{4}}$ . This is called the absolute refractive index of the medium. Question 3 What is absolute refractive index? A ray of light through the optical centre of a lens passes without suffering any deviation.