what will be the sign of distance by
Answers
Answer:
Object distance (u) for a concave mirror or convex mirror is always negative because an object is always placed to the left side of the mirror and the distances towards the left side of the mirror are always negative.
(b) In case of a concave mirror, if the image is formed on the left side of the mirror, then the image distance (v) will be negative and if the image is formed on the right side of the mirror, then the image distance (v) will be positive. This is because distances measured to the left of the mirror are negative and to the right of the mirror is positive.
(c) Image distances (v) for a convex mirror is always positive because the image is always formed behind the mirror.
Answer:
For convex lens
the object distance is -ve.
image distance is +ve for real image and -ve for virtual image.
focal length is +ve.
For concave lens
the object distance is -ve
image distance is -ve
focal length is -ve.
The rule is simple,
Distances measured from optic center to the right are considered +ve and the distances measured from optic center to the left are -ve.
if you draw a line from the optic center and move towards right i.e., along the +ve x-axis then the sign is +ve.
similarly if you move towards the -ve x-axis, the distances are -ve.
for converging lens, the light rays meet at a point after refraction, thus it has positive focal length.
For diverging lens the light rays appear to meet at a point after refraction, thus virtual focal length and -ve sign.