Explain the image formation by a concave mirror when object is between F and P,,Object at F,,Object between F and C,,Object at C,Object beyond C,,Object at infinity.

Dear Student!!

I. When the object is at infinity.

 

 

 

 

II. When the object is behind the centre of curvature.

 

 

 

 

III. When the object is at the centre of curvature.

 

 

 

 

IV. When the object is between the centre of curvature (C) and focus (F).

 

 

 

 

 

V. When the object is at focus (F).

 

 

 

 

VI. When the object is placed between the focus (F) and the pole (P).

The discussion can be summarized in the table given below:

Object position

Image position

Size of image

Nature of image

At infinity

Focus (F)

Point sized

Real

Beyond C

Between F and C

Small

Real and inverted

At C

At C

Same as that of the object

Real and inverted

Between C and F

Behind C

Enlarged

Real and inverted

At F

At infinity

Dear Studentghly enlarged

Real and inverted

Between F and P

Behind mirror

Enlarged

Virtual and erect

  • 8

(i) In case of object between F and P:-

the rays diverge after reflection........... Hence the image is :---

  • behind the mirror
  • virtual
  • erect 
  • enlarged

(ii) in case of object at F:-

  • the rays emerge parallel after reflection. Since parallel rays are assumed to meet at infinity, the image is at infinity..

(iii)In case of object between F and C:----

the image is:------

  • beyond C
  • real
  • inverted
  • magnified

(iv) in case of object at C:-

the image is:---

  • at C
  • real
  • inverted
  • the image is of the same size as the object.

(v)in case of object beyond C:-

image is :-----

  • between C and F
  • real
  • inverted
  • diminished

 (vi) in the case of object at infinity:-

When the object is very far off, like sun, the rays coming from it are parallel to each other. .......... Hence the image is:----

  • at F
  • real
  • inverted
  • diminished
  • 2
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