If the magnification of a virtual image formed by an object 10cm from a convex less is 3, then the focal length of the lens is

Iyede Godstime

9 years ago

Little error was made: 3=v/10

v=30





d formula for calculating focal length is always 1/f=1/u + 1/v



since it is virtual and not real, we use:

1/f=1/u - 1/v

WONDER GIRL

9 years ago

M=v/u. 3=v/10 (crosmultiply) v=30 in virtual images lens formular is 1/f=1/u-1/v 1/f=1/10-1/30 1/f=3-1/30 .f=15

Award0001

2 years ago

guys just be careful whenever dealing with lens or mirrors of converging types
since it forms 5 Cases, only case 5 forms a virtual image which means the focus is virtual/negative and thr image is also virtual/negative
-1/f = 1/u - 1/v

in case 3 the image is also magnified but has a real focus and real image
1/f = 1/u + 1/v

Read up all five caes for a converging mirror and converging lens🤲

Akpadolu

9 years ago

i don't understand y minus is used in d solving instead of plus .can sumone help out there????

Gddhhcv

2 years ago

Verified ✅💯

Gurzweal

9 years ago

yes drapu you are correct

oredos

9 years ago

M(u-f)=f

3(10-f)=f

30-3f=f

30=-3f+f

30/2=15

Elbrain

9 years ago

= 10 X 3 = 30

= 30/2

=15