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NCERT Rules Ray Diagram Science Chapter Class 10

Rules for obtaining ray diagram formed by convex mirror

1. A ray incident parallel to the principal axis of a convex mirror after reflection will appear to comefrom the focus.
2. A ray directed towards the focus of a convex mirror after reflection will become parallel to the principal axis.
3. A ray directed towards center of curvature of convex mirror is reflected back along the same path .
4. A ray incident obliquely at the pole of convex mirror is reflected obliquely by making equal angle of incidence and reflection with the principal axis.

Sign Convention:

The object should be placed on the left side and front of the image.

All the distance should be measured from the pole of the mirror.

The distance measured against direction of incident ray is taken negative.

The distance measured along direction of incident ray is taken positive.

The perpendicular distance above principal axis is +ve.

The perpendicular distance below principal axis is -ve.

Mirror Formula:

1/v + 1/u = 1/f

v =position of image

u = Position of object

f = Focal length

Magnification:

The magnification produced by a spherical mirror is the ratio of height of image to height of object.

m = h_i / h_o = -v/u

|m|>1 Magnified

|m|<1 Diminished

|m|=1 Same Size

Note :If m is –ve the image is real and inverted.

Note : If m is +ve the image is virtual and erect.