Light long 3

Question 1

Uses of concave mirrors ?

Answer 1

Concave mirrors are commonly used in torches, search-lights and vehicles headlights and as shaving mirrors to see a larger image of the face.
dentists use concave mirrors to see large images of the teeth of patients. Large concave mirrors are used to concentrate sunlight to produce heat in solar furnaces.

Question 2

Uses of convex mirrors ?

Answer 2

Convex mirrors are commonly used as rear-view mirrors in vehicles. These mirrors are fitted on the sides of the vehicle, enabling the driver to see traffic behind him. Convex mirrors are preferred because they always give an erect, though
diminished, image.

Question 3

What is the New Cartesian Sign Convention ?

Answer 3

Just read — this convention, the pole (P) of the mirror is taken as the origin. The principal axis of the mirror is taken as the x-axis (X’X) of the coordinate system. The conventions are as follows –
(X’X) of the coordinate system. The conventions are as follows –

(i) The object is always placed to the left of the mirror.

(ii) All distances parallel to the principal axis are measured from the pole of the mirror.

(iii) All the distances measured to the right of the origin (along + x-axis) are taken as positive while those measured to the left of the origin (along – x-axis) are taken as negative.

(iv) Distances measured perpendicular to and above the principal axis (along + y-axis) are taken as positive.

(v) Distances measured perpendicular to and below the principal axis (along –y-axis) are taken as negative.