List the sign conventions reflection of light by spherical mirrors. Draw a
diagram and apply these conventions in the determination of focal
length of a spherical mirror which forms three times magnified real
image of an object placed 16 cm in front of it.
Answers
Answer:
Sign conventions for spherical mirrors:
I. Objects are always placed to the left of the mirror i.e. light must fall on the mirror from left to right.
II. All distances are measured from the pole of the mirror.
III. Distances along the direction of the incident ray ( along positive X - axis) are taken as positive, while distances along the direction of the reflected ray (along negative X-axis) are taken as negative.
IV. Heights measured perpendicular to and above the principal axis (along positive Y-axis) are taken as positive.
V. Heights measured perpendicular to and below the principal axis (along negative Y-axis) are taken as negative.
image
Given,
m = -3 (Real image is inverted always)
u = -16 cm
image
image
Explanation:
SIGN OF CONVENTIONS
1 All distances should be measured from pole
2 If we measure the object distance in the direction of incident light taken as positive if we take opposite to incident light taken as negative
3 If we measure height of the object is taken as positive when measured upwards from the principal axis and measured downwards the principal axis taken as negative