Check sibling questions

A student wants to project the image of a candle  flame on the walls of the school laboratory by  using a mirror.  


(a) Which type of mirror should he use and why? 

(i) Convex mirror, it forms virtual image  

(ii) Concave mirror, it forms virtual image  

(iii) Concave mirror, it forms real image  

(iv) Convex mirror, it forms real image  



Since the student wants image on a wall , it has to be a real image


Now, let’s check both mirrors

  • Convex mirrors always produce virtual images . It cannot be used to produce images on the screen.
  • Concave mirrors produce real images on the screen in all cases except when the object is between pole and focus , therefore students should use a concave mirror because it forms real images.

So, the correct answer is (iii) Concave mirror, it forms a real image.  

(b) At what distance, in terms of focal length ‘f’ of the  mirror, should he place the candle flame to get the  magnified image on the wall?  

(i) At F 

(ii) Between F and C  

(iii) At C 

(iv) At infinity  



In a concave mirror

  • We get a magnified and real image when object is placed between F and C



So, the correct answer is (ii) Between F and C  

(c) To get the diminished image of the candle flame,  the object must be placed at: 

(i) infinity 

(ii) at C  

(iii) between F and C 

(iv) At F  



For a concave mirror

  • When rays are coming from infinity , a concave mirror will produce a diminished image on the screen.


And for other cases - please check Concave mirror ray diagram


So, the correct answer is (i) at infinity 


(d) If the image formed by this mirror is inverted and  real, the magnification will be:  

(i) Positive 

(ii) Negative  

(iii) Either of them 

(iv) None of the above  



According to the Cartesian sign convention for spherical mirrors, images formed on the left side of the mirror are signed as negative .



So, the correct answer is (ii) negative  

(e) A virtual image formed by concave mirror is: 

(i) erect and enlarged  

(ii) erect and diminished  

(iii) inverted and diminished  

(iv) inverted and enlarged  


For a concave mirror

  • Virtual image is formed when an object is placed between pole and focus .
  • And, Image formed is enlarged .


So, the correct answer is (i) erect and enlarged 

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Maninder Singh

CA Maninder Singh is a Chartered Accountant for the past 13 years and a teacher from the past 17 years. He teaches Science, Economics, Accounting and English at Teachoo