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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.

CBSE Class 12 important electrostatic questions

Questions having one mark each:
1. Write the S.I unit of
i. electric field intensity
ii. Electric dipole moment.
iii electric Potential
2. How does the coulomb force between two point charges depend upon the dielectric constant of the intervening medium?
3. Draw an equipotential surface for a system, consisting of two charges Q, -Q separated by a distance ‘r’ apart.
4. Show graphically the variation of charge ‘q’ with time’t’ when a condenser is charged.
5. What orientation of an electric dipole in a uniform electric field would correspond to stable equilibrium?

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