Question

a 5 cm tall object is placed at a distance of 30 cm from a convex mirror of focal length 15 cm. find the position, size and nature of the image formed.

Answer 1

Use the formula 1/v + 1/u = 1/f

u= -30cm and f=15cm.

We get v as +10cm.

Positive sign indicates that it is a virtual image.

Magnification is given by the formula -v/u i.e,

-10/-30=1/3

Therefore size of image would be 5/3 cm.

Answer 2

Distance of object from pole(u) = -30cm

Distance of focus from pole(f) = -15cm

Height of the object = 5cm

MIRROR FORMULA

1/f=1/v+1/u

1/-15=1/v+1/-30

1/v=1/-15+1/30

1/v=1/30-1/15

1/v=1-2/30

1/v=-1/30

v=-30

MAGNIFICATION

m=-v/u

m=-(-30)/-30

m=30/-30

m=-1

Image formed is real inverted and same size of object position of image is left side of pole