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Class 10 CBSE Reflection and refraction extra questions

Q1. What is the difference between reflection and refraction?
Q2.Refraction is caused by
a. different wave speeds.
b. more than one reflection.
c. displaced images.
d. bending.

Q3. What will happen to ray of light when it travels from rarer medium to a denser medium ?

Q4. What is absolute refractive index ?
Q5. If refractive index of glass is 1.65, What is the speed of light in glass. ?


1) If X is any point in the interior of triangle ABC. Prove that XA+XB+XC> (1/2) (AB+BC+CA).

2) Using the factor theorem, factorize the polynomial
x4 + 2×3 – 13×2 – 14x + 24.

3) Factorize: 8×4 + 2×2 -1.
4)The sides of a triangle are in the ration of 13 : 14 : 15 and its perimeter is 84 cm.
Find the area of the triangle. Also find the altitude of the triangle corresponding to the longest side.

Top Known Scientist in Heat and Thermodynamics Field

James Prescott Joule (1818 – 1889)
•He was an English physicist and brewer, born in Salford, Lancashire.
•He received his early education at home
•He studied for sometime under John Dalton
•Joule studied the nature of heat, and discovered its relationship to mechanical work .
•His first major research was concerned with determining the quantity of heat produced by an electric current and, in 1840, Joule discovered a simple law connecting the current and resistance with the heat generated.

Mirror and Lens Problems

Glossary of Mirror and Lenses

Plane Mirror
A plane mirror is a mirror with a planar reflective surface. For light rays striking a plane mirror, the angle of reflection equals the angle of incidence.It always form virtual image

Concave or Converging Mirrors
A curved mirror that has its center farther away from you than its edges is called a concave mirror. A concave mirror tends to reflect parallel rays through a point called its focus – in other words a concave mirror converges light. Therefore concave mirrors are often referred to as converging mirrors. This converging effect makes sense if you imagine a concave mirror to be an array of small plane mirrors.You can demonstrate the converging of parallel light rays by a concave mirror quite dramatically for yourself. A relatively small concave mirror placed in the sun will gather enough light to ignite a small piece of paper quite quickly

Convex or Diverging Mirrors

The Age of the Universe( Big Bang)

One question has always fascinated the scientists ” When the universe began?” . Current Thinking believes that Universe began as a singularity in space and Time. The singularity is called as Big Bang. It is believed at this time everything was condensed into very small space. After that the Universe has been continuously expansion mode.

A Astronomer Edwin Hubble discovered in 1929 the rate of expansion of Universe i.e the rate at which the galaxies are receding from each other. That law is called Hubble Law. As per Law, if the two galaxies are at distance R,Their present relative velocity of separation is given by

How to increase your concentration on Studies

1. Find a place where you go only to study. It should be quiet area .Identify your distractions. Find ways to decrease them or to postpone them until study breaks e.g., taking the phone off the hook, turning off Whatapps. If using a computer, exit out of email and messengers.

2. Always sit straight in a chair at a desk, start out with questions about the material, outline chapters, underline key phrases after reading section, write notes in margins, ask yourself what you have learned.Take good notes of the chapter and revise them also.If you have difficulty understanding any thing ,search it in other books and internet. If it is not resolved,write it down to discuss with Friends and teacher

3) Doing a big task may seems to be impossible to you. So Divide your work into smaller manageable tasks that can be completed in a short period of time. First Push yourself to complete one small task, then move on to the next task. Focus on one small task at a time.