Saved Bookmarks
| 1. |
An object is held at a distance of 20 cm from a concave lens of focal length 20cm what is the position and the size of the image if the object is 2 cm heigh |
|
Answer» Answer: Explanation: f=-20cm v=-15 1 over v MINUS 1 over U equals 1 over f fraction numerator begin display STYLE 1 end style over denominator begin display style NEGATIVE 15 end style end fraction minus fraction numerator begin display style 1 end style over denominator begin display style u end style end fraction equals fraction numerator begin display style 1 end style over denominator begin display style negative 20 end style end fraction fraction numerator begin display style 1 end style over denominator begin display style u end style end fraction equals fraction numerator begin display style 1 end style over denominator begin display style 20 end style end fraction minus fraction numerator begin display style 1 end style over denominator begin display style 15 end style end fraction fraction numerator begin display style 1 end style over denominator begin display style u end style end fraction equals fraction numerator begin display style 3 minus 4 end style over denominator begin display style 60 end style end fraction fraction numerator begin display style 1 end style over denominator begin display style u end style end fraction equals fraction numerator begin display style negative 1 end style over denominator begin display style 60 end style end fraction u equals negative 60 m equals v over u equals fraction numerator H e i g h t space o f space i m a g e left parenthesis h subscript i right parenthesis over denominator H e i g h t space o f space o b j e c t left parenthesis h subscript o right parenthesis end fraction fraction numerator negative 15 over denominator negative 60 end fraction equals h subscript i over 5 h subscript i equals 5 over 4 equals 1.25 c m |
|