Question

given a spherical mirror whose radius of curvature is+20cm what is focal length of this mirror does it form a real or virtual image

Answer 1

CONCEPT :

We know that focal length of concave mirror is always positive and convex mirror is always negative

We know that concave mirror form real and inverted image

we know that convex mirror always foam vertical and erect image

GIVEN :

radius of curvature is+20cm

FIND :

Radius of curvature and nature of image

$\mapsto$ focal length = Radius of curvature / 2

$\mapsto$ focal length = +20 cm/2

$\mapsto$ Focal length = +10 cm

Hence, the focal length of mirror is + 10 cm

CONCLUSION :

As the focal length is half of radius of curvature and thus ,f = +10cm. Since, sign is positive it means the mirror is convex and it will always form virtual erect and diminished image.