A student took three concave mirrors of different focal lengths and performed the experiment to see the…
A student took three concave mirrors of different focal lengths and performed the experiment to see the image formation by placing an object at different distances with these mirrors as shown in the following table.
Case No. | Object-distance | Focal length
I | 45 cm | 20 cm
II | 30 cm | 15 cm
III | 20 cm | 30 cm
Now answer the following questions :
(a) List two properties of the image formed in Case I.
(b) In which one of the cases given in the table, the mirror will form real image of same size and why ?
(c) Name the type of mirror used by dentists. Give reason why do they use such type of mirrors.
Solution
(a) Real, inverted, diminished (Any two)
(b) Case II
Because focal length of mirror is 15 cm, object distance is 30cm which means the object is placed at C.
(c) Dentists use concave mirrors
Because concave mirror forms erect and enlarged image when object is very close to the mirror.