A mirror and a source of light are situated at the origin and at a point on respectively. A ray of light from the source strikes the mirror and is reflected. If the direction ratios of the normal to the plane are proportional to , then direction cosines of the reflected ray are |
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a) |
b) |
c) |
d) |

A mirror and a source of light are situated at the origin and at a point on respectively. A ray of light from the source strikes the mirror and is reflected. If the direction ratios of the normal to the plane are proportional to , then direction cosines of the reflected ray are |
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a) |
b) |
c) |
d) |

1 Answer

127 votes

**(d)**

Let the source of light be situated at , where,

Let be the incident ray, be the reflected ray and be the normal to the mirror at

Direction ratios of are proportional to and so its direction cosines are 1, 0, 0

Direction cosines of are

Let be the direction cosines of the reflected ray . Then,

Hence, direction cosines of the reflected ray are

127 votes

127