GRADE 10 LIGHT

Assertion(A) : The centre of curvature is not a part of the mirror. It lies outside its reflecting surface.
Reason (R) : The reflecting surface of a spherical mirror forms a part of a sphere. This sphere has a centre.

• (a) Both A and R are true and R is the correct explanation of A.
  
  
  

• (b) Both A and R are true but R is not the correct explanation of A.

• (c) A is true but R is false.

• (d) A is false but R is true.

Assertion (A) : A ray passing through the centre of curvature of a concave mirror after reflection, is reflected back along the same path.

Reason (R): The incident rays fall on the mirror along the normal to the reflecting surface.

• (a) Both A and R are true and R is the correct explanation of A.
  
  
  

• (b) Both A and R are true but R is not the correct explanation of A.

• (c) A is true but R is false.

• (d) A is false but R is true.

Assertion(A) : Light travels faster in glass than in air.
Reason (R) : Glass is denser than air.

• (a) Both A and R are true and R is the correct explanation of A.
  
  
  

• (b) Both A and R are true but R is not the correct explanation of A.

• (c) A is true but R is false.

• (d) A is false but R is true.

Assertion(A) : Refractive index has no units.
Reason (R) : The refractive index is a ratio of two similar quantities.

• (a) Both A and R are true and R is the correct explanation of A.
  
  
  

• (b) Both A and R are true but R is not the correct explanation of A.

• (c) A is true but R is false.

• (d) A is false but R is true.

Assertion(A): Virtual images are always erect.
Reason (R) : Virtual images are formed by diverging lenses only.

• (a) Both A and R are true and R is the correct explanation of A.
  
  
  

• (b) Both A and R are true but R is not the correct explanation of A.

• (c) A is true but R is false.

• (d) A is false but R is true.

The radius of curvature of a mirror is 20cm the focal length is

         

         

         

         

• a. 20cm

• b. 10cm

• c. 40cm

• d. 5cm

Focal length of plane mirror is         
         
         
         

• (a) At infinity

• (b) Zero

• (c) Negative

• (d) None of these

In order to obtain a magnification of, -0.6 (minus 0.6) with a concave mirror, the object must be placed:

• (a) At the focus

• (b) Between pole and focus

• (c) Between focus and center of curvature

• (d) Beyond the center of curvature

A concave lens form the image of an object which is :

• (a) Virtual inverted and diminished
  
  
  

• (b) Virtual upright and diminished

• (c) Virtual inverted and enlarged

• (d) Virtual upright and enlarged

Assertion(A) : For observing traffic at back, the driver mirror is convex mirror.
Reason (R) : A convex mirror has much larger field of view than a plane mirror.

• (a) Both A and R are true and R is the correct explanation of A.
  
  
  

• (b) Both A and R are true but R is not the correct explanation of A.

• (c) A is true but R is false.

• (d) A is false but R is true.