Question

Find the focal length of a convex mirror where m=4/7 and forms a image at distance of 20cm​

Answer 1

${\Large{\boxed{\pmb{\mathcal{\red{AnSwer~:}}}}}}$

• Focal length = 5cm

Answer 2

Answer:

Given:

size of object, o=+7cm

distance of object ,u=−27cm

focal length of concave mirror, f=−18cm

let us take size of image=I

so, mirror formula is 

v1+u1=f1

so, putting values of u and v,

v1=−181−−271

v1=−541

v=−54cm

so, image is formed on object side only.

magnification,

m=u−v=oI

m=−−27−54=7I

I=−14cm

so, image is double in size to that of object.

Nature: real, inverted and magnified image.