1. The principal focus of a concave mirror is a point on its principal axis to which all the light rays which are parallel and close to the axis, converge after reflection from the concave mirror.

    The principal focus of a concave mirror is a point on its principal axis to which all the
    light rays which are parallel and close to the axis, converge after reflection from the concave mirror.

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  2. The child is suffering from myopia. This defect can be corrected by using a concave lens of suitable focal length.

    The child is suffering from myopia. This defect
    can be corrected by using a concave lens of suitable focal length.

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  3. For a normal human eye, this distance is 25 cm. The far point of the eye is the maximum distance to which the eye can see the objects clearly. The far point of the normal human eye is infinity.

    For a normal human eye, this distance is 25 cm. The far point of the eye is the maximum distance to which the eye can see the objects clearly. The far point of the normal human eye is infinity.

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  4. The person is able to see nearby objects clearly, but he is unable to see objects beyond 1.2 m because the image formed in front of the retina. To correct this defect of vision, he must use a concave lens. The concave lens will bring the image back to the retina.

    The person is able to see nearby objects clearly, but he is unable to see objects beyond
    1.2 m because the image formed in front of the
    retina.
    To correct this defect of vision, he must use a concave lens. The concave lens will bring
    the image back to the retina.

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