Class 10 Chapter 10 – Light – Reflection and Refraction
Light – Reflection and Refraction
Spherical mirror
Image Formation by Spherical Mirrors
Images formed by concave mirror
Magnification produced by a spherical mirror gives the relative extent to which the image of an object is magnified with respect to the object size.
It is expressed as the ratio of the height of the image to the height of the Object. It is usually represented by the letter m.
If h_{1} is the height of the object and h_{0} is the height of the image, then The magnification m produced by a spherical mirror is given by
Refraction through a Rectangular Glass Slab
The following are the laws of refraction of light.
(i) The incident ray, the refracted ray and the normal to the interface of two transparent media at the point of incidence, all lie in the same plane.
(ii) The ratio of sine of angle of incidence to the sine of angle of refraction is a constant, for the light of a given colour and for the given pair of media. This law is also known as Snell’s law of refraction.
If i is the angle of incidence and r is the angle of refraction, then,
Sin i =constant
Sin r
This constant value is called the refractive index of the second medium with respect to the first
The Refractive Index
Image Formation in Lenses Using Ray Diagrams
Images formed by convex lens
Images formed by concave lens
Lens Formula and Magnification
The power of a lens is defined as the reciprocal of its focal length. It is represented by the letter P. The Power P of a lens of focal length f is given by
P=1/f
The SI unit of power of a lens is ‘dioptre’. It is denoted by the letter D.
If f is expressed in metres, then, power is expressed in dioptres. Thus, 1 dioptre is the power of a lens whose focal length is 1 metre. 1D = 1m–1.
You may note that the power of a convex lens is positive and that of a Concave lens is negative.
Opticians prescribe corrective lenses indicating their powers.
Course Curriculum

Lessons
 Class 10 Chapter 1 – Chemical Reactions and Equations
 Class 10 chapter 2 – Acids, Bases and Salts
 Class 10 Chapter 3 – Metals and Non Metals
 Class 10 Chapter 4 – Carbon and its Compounds
 Class 10 Chapter 5 – Periodic Classification of Elements
 Class 10 Chapter 6 – Life Processes
 class 10 chapter 7 – Control and Coordination
 Class 10 Chapter 8 – How do Organisms Reproduce?
 Class 10 Chapter 9 – Heredity and Evolution
 Class 10 Chapter 10 – Light – Reflection and Refraction
 Class 10 Chapter 11 – The Human Eye and the Colourful World
 Class 10 Chapter 12 – Electricity
 Class 10 Chapter 13 – Magnetic Effects of Electric Current
 Class 10 Chapter 14 – Sources of Energy
 Class 10 Chapter 15 – Our Environment
 Class 10 Chapter 16 – Management of Natural Resources

Question Bank
 Class 10 Question Bank Chapter 1 – Chemicals Reactions and Equations
 Class 10 Question Bank Chapter 2 – Acids, Bases and Salts
 Class 10 Question Bank Chapter 3 – Metals and non metals
 Class 10 Question Bank Chapter 4 – Carbon and its Compounds
 Class 10 Question Bank Chapter 5 – Periodic Classification of Elements
 Class 10 Question Bank Chapter 6 – Life processes
 Class 10 Question Bank Chapter 7 – Control and Coordination
 Class 10 Question Bank Chapter 8 – How do Organisms Reproduce?
 Class 10 Question Bank Chapter 9 – Heredity and Evolution
 Class 10 Question Bank Chapter 10 – Light – Reflection and Refraction
 Class 10 Question Bank Chapter 11 – The Human Eye and the Colourful World
 Class 10 Question Bank Chapter 12 – Electricity
 Class 10 Question Bank Chapter 13 – Magnetic effects of electric current
 Class 10 Question Bank Chapter 14 – Sources of Energy
 Class 10 Question Bank Chapter 15 – Our environment
 Class 10 Question Bank Chapter 16 – Management of Natural Resources