Ravu -_-
Ravi is given lenses with powers + 5 D, – 5 D, + 10 D,- 10 D and -20 D. Considering a pair of lenses at a time, which two lenses will he select to have a combination of total focal length when two lenses are kept in contact in each case:
i. -10 cm
ii. 20 cm
iii. -20 cm
Answer:
ok no problem we will meet at 11 pm