Question

A 10 cm long stick is kept in front of
a concave mirror having focal length
of 10 cm in such a way that the end
of the stick closest to the pole is at a
distance of 20 cm. What will be the
length of the image?​

Answer 1

to calculate this sort of question, we make use of magnification and mirror equations.

- The mirror and magnification equations, make use of ray diagrams to predict the type, orientation, location and size of image formed from an object.

⇒The mirror equation gives a numerical relationship of the object distance(u), image distance (v) and the focal length. This equation is given below:

1/f = 1/u + 1/v

- this is the equation we will use to work out this question.

⇒ On the other hand, the magnification equation gives a numerical relationship of the ratio between the object distance - image distance as compared to the ratio of the object height (h₁) to the image height (h₂).

The equation is given as follows:

u/v = h₁/h₂

⇒ In the diagram below I have attached the steps in calculating the length of the image in the question above: