Question

what is sign convention

Answer 1

Sign Convention for Spherical Mirror: Cartesian Sign Convention: In the case of spherical mirror all signs are taken from Pole of the spherical mirror, which is often called origin or origin point. This sign convention is known as New Cartesian Sign Convention.

Answer 2

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Sign conventions are also called as new cartesian sign convention which are the rules to be followed while dealing with reflection of light by spherical Mirrors for refraction of light by lens.

The sign convention for reflection by spherical Mirrors :-

• The object is always leads to the left of the mirror. This implies that the light from the object falls on the mirror from the left hand side.
• All distance is parallel to principal Axis are measured from the pole of the mirror.
• All the distance is measured to the right of the origin along the positive x-axis are taken as positive wild Rose measured to the left of the origin along the negative x-axis are taken as negative.
• Distances measured perpendicular to and above the principal Axis along the positive y-axis are taken as positive.
• Distances major perpendicular to and below the principal Axis along the negative y-axis are taken as negative.

The Sign convention for this spherical lenses :-

The sign convention for the spherical lenses are similar to that of for the spherical Mirrors.

Only one difference is there which is that the measurements are taken from the optical centre of the lens.

According to this sign convention, the focal length of convex lens is positive and the focal length for concave lens is negative.

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