Question

problem on sign convention of convex and concave lens and mirror

Answer 1

converging lenses, the focal length is always positive, while diverging lenses always have negative focal lengths. However, these conventions are arbitrary, and physicists could ...

Answer 2

Hi, listen
you have problems to learn sign convention of lens
I tell you short method which will become easier to you
Now firstly we will see concave lens =
1) upside principal axis the object is negative but when we see backside the mirror than it is positive.
2) downside image of principal axis the image is positive but the backside of mirror it is negative.
3) It is converging so it's focal length is always negative
similarly you can see the convex lens will opposite of concave and the focal length of convex is positive.
$okk$