The focal length of concave lens is 25 cm. Then its power will be |
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(a) |
4 D |
(b) |
-4 |
(c) |
-4 D |
(d) |
All of these |

The focal length of concave lens is 25 cm. Then its power will be |
|||||||

(a) |
4 D |
(b) |
-4 |
(c) |
-4 D |
(d) |
All of these |

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