mirror problem?

The side-view mirror of an automobile has a radius of curvature of 11.5 cm. The mirror produces a virtual image one half the size of the object. How far is the object from the mirror? answer in units of cm.

Comments

  • ans: object is 5.75 cm. away from the mirror.

    here's how:

    1)since it is a convex MIRROR so focal length, f=R/2 where R is the radius of curvature. so f=11.5/2 = 5.75 cm.

    2)Since the mirror produces a virtual image one half the size of the object, so magnification is 1/2 i.e 0.5 Also magnification for a MIRROR, m = -v/u, where v is the image distance from mirror and u is the object distance from mirror.

    So. -v/u = 1/2

    =>v = -u/2

    Using MIRROR formula: 1/f = 1/u + 1/v

    here f = 5.75, v = -u/2.

    Put the values and u'll get the answer u=5.75 cm. (take care of sign i.e put value of v along with sign)

  • "closer that it appears"

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