Question

58. The image formed by a convex mirror of focal length 30 cm is one-quarter of the object. Select the row containing the correct value of object and image distance. Object distance (u) (in cm) Image distance (v) (in cm) (a) -90 +22.5 (b) - 22.5 -90 6 - 90 - 22.5 (d) - 90 +90 ම​

Answer 1

Answer:

90 cm

Explanation:

90cm

The focal length of the convex mirror is f=30cm and the magnification of the image is m=1/4

We have to calculate the object distance u.

According to sign convention, the measurements along the direction of light are taken as positive and opposite to the light taken as negative. The transverse measurement above the principal axis is taken as positive and below the principal axis is taken as negative.

Thus, f=+30cm and m=+1/4=+0.25

Using formula, m=

f−u

f

or mf−mu=f

or u=

m

mf−f

=

m

m−1

f=

0.25

0.25−1

(30)=−90cm