Question

An object of length 2.5cm is placed at a 1.5f from a concave mirror where f is magnitude of focal length of mirror. The length of object is perpendicular to principal axis . Then which of following will be correct . (i) image is 5 cm long (ii) image is 10 cm long (iii) image is inverted (iv)image is erect

Answer 1

Bro 1 and 3 both are correct

Answer 2

Focal length F=−f

and u=−1.5f

1u+1v=1F

1−1.5f+1v=−1f

1v=11.5f−1f

=−−13f

v=−3f

Now m=−vu=−3f1.5f=−2

or h2h=−2

or h2=−2h1=−5cm

the image is 5 cm long.

The minus sign shows that it is inverted.