Light: Reflection And Refraction
Very Short Answer Type Questions
Q.1. What is meant by relative refractive index? 
Ans. When a light ray travels from one medium to another medium is called relative refractive index.
it is donated by 1u2.

Q.2. Name the lens towards the object and eye in microscope.(imp)
Ans.  The lens towards the object is called objective lens and that towards the eye is called as eye piece .

Q.3. What is spherical mirror ? Write its types.
Ans. The mirror whose reflecting surface is spherical is called spherical mirror.
Spherical mirror are two types :
(1) Spherical mirror, (ii) Convex mirror.

Q.4. What is power of lens ? 
Ans. The reciprocal of length (in metre) is called power of lens, its unit is dioptre.

Q.5. What is lens ? Write its types.
Ans. The transport medium covered with two spherical surface is called lens. Lenses are of two types.(1) Concave lens, (2) Convex lens.

Q.6. Which lens is used as rear view mirror in vehicles ? Why ? (mp 2010) 
Ans. In convex mirror the diminished and virtual image of object is formed, so the convex mirror is used in vehicles as rear view mirror.

Q.7. What is meant by rarer and denser medium ? (mp 2009) 
Ans. The medium whose optical density is less, are called denser medium which the medium whose optical density is less, are called rarer medium.

Q.8. What is meant by refraction of light ? 
Ans. The phenomenon by which a ray of light deviates from its original path, while travelling from one optical medium to another optical medium is called refraction.

Short Answer Type Questions
Q.1. The radius of curvature of a spherical mirror is 20 cm. What is ots focal length ?(imp)
Ans. R=20.cm
                  F=R/2
                  F=20/2=10.cm.

Q.2. What is laws of reflection: 
Ans. (i) The angle of reflection is always equal to the angle of incidence.
(ii) The incident rays, reflected rays and the normal, all lie in the same plane.

Q.3. State the name of mirror which conform an erect and magnified image of object ? 
Ans. Concave mirror, when object is placed at between pole and focus of a concave mirror then the magnified and erect image of object is obtained.


Q.4. Where should the object be placed so as to form its real, inverted and magnified image by a concave mirror? (Sow the diagram)
Ans. To obtain a real inverted and magnified image by a concave mirror, the object should be placed on the principal focus F.

Long Answer Type Questions
Q.1. A concave lens of focal length 15.cm forms am image 10 cm from the lens. How far the object placed form the lens? 
Ans. 
Given  focal length of concave lens f= -15 cm
             Image distance v = -10 cm 
             Object distance u=?