Question

the focal length in a concave len is +or - ????​

Answer 1

Ello..✌✌

The focal length of concave lens is negative.

Answer 2

Answer:it is negative (-)

Explanation:

To examine whether the focal length of mirror is +ve or -ve we need to study cartesian plane which tells us that left side of plane is negative, right side of plane is positive,up side is positive and down side is negative. So focal length of concave mirror is left side so it is negative and focal length of convex mirror is right side so it is positive.