A lamp rated at hangs over the middle of a round table with diameter at a height of . It is replaced by a lamp of and the distance to the table is changed so that theillumination at the centre of the table remains as before. The illumination at edge of the table becomes times the original. Then is |
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a) |
b) |
c) |
1/4 |
d) |

A lamp rated at hangs over the middle of a round table with diameter at a height of . It is replaced by a lamp of and the distance to the table is changed so that theillumination at the centre of the table remains as before. The illumination at edge of the table becomes times the original. Then is |
|||||||

a) |
b) |
c) |
1/4 |
d) |

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