CBSE Class 12-science Answered
An object 4cm in size, is placed at 25cm infront of a concave mirror
of focal length 15cm. At what distance from the mirror whould a screen be
placed in order to obtain a sharp image?Find the nature and the size of the
image.
Asked by amarapurevathi | 05 Oct, 2018, 12:22: PM
focal length = f = - 15 cm
object distance = u = -25 cm
image distance = v = ?
hi = ?
ho = 4 cm
Mirror formula,
1/v + 1/u = 1/f
![1 over f space equals space 1 over u plus 1 over v
rightwards double arrow fraction numerator 1 over denominator negative 15 end fraction equals fraction numerator 1 over denominator negative 25 end fraction plus 1 over v
rightwards double arrow space fraction numerator 1 over denominator negative 15 end fraction plus 1 over 25 space equals space 1 over v
rightwards double arrow space 1 over v equals fraction numerator 25 minus 15 over denominator negative 375 end fraction
rightwards double arrow space v space equals negative space 37.5 space c m space](https://images.topperlearning.com/topper/tinymce/cache/c490bb7e86b02de824ff20e6f6befc3a.png)
![m equals fraction numerator negative v over denominator u end fraction equals h subscript i over h subscript o
rightwards double arrow space m space equals fraction numerator negative left parenthesis negative 37.5 right parenthesis over denominator negative 25 end fraction equals h subscript i over 4
h subscript i space equals space 150 over 25 equals space minus 6 space c m](https://images.topperlearning.com/topper/tinymce/cache/315f9e8db13714bcd62cfad139a85209.png)
Thus, to get image of object sharp it has to be placed at 37.5 cm
Size of image is 6 cm
As the height of object is more and negative, nature of image is real, inverted and magnified.
Answered by Shiwani Sawant | 05 Oct, 2018, 14:25: PM
Concept Videos
CBSE 12-science - Physics
Asked by pushpamagadum21 | 09 Jul, 2024, 20:43: PM
CBSE 12-science - Physics
Asked by amishavasave56.12dgatl | 27 Aug, 2021, 17:25: PM
CBSE 12-science - Physics
Asked by raushankumarmushkipur | 02 Apr, 2021, 10:08: AM
CBSE 12-science - Physics
Asked by prakriti12oct | 11 Feb, 2020, 14:48: PM
CBSE 12-science - Physics
Asked by prakriti12oct | 27 Jun, 2019, 02:20: AM
CBSE 12-science - Physics
Asked by polyrelation | 15 Mar, 2019, 16:42: PM
CBSE 12-science - Physics
Asked by mridulabarua05 | 11 Feb, 2019, 13:10: PM
CBSE 12-science - Physics
Asked by mridulabarua05 | 07 Feb, 2019, 09:10: AM
CBSE 12-science - Physics
Asked by mridulabarua05 | 02 Feb, 2019, 11:23: AM
CBSE 12-science - Physics
Asked by Aadeshveersingh03 | 07 Jan, 2019, 07:57: AM