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| Numerical - 01 |
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| 01. A 4.5 cm needle is placed 12 cm away from a convex mirror of focal length 15cm. Give the location of the image and the magnification. Describe what happens as the needle is moved farther from the mirror. |
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| Suggested solution: |
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| U = -12 cm, f = +15 cm, v = ? |
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| On simplification, v = +6.7 cm |
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| The +ve sign indicates that the image is formed behind the mirror. |
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| The positive sign indicates that the image is erect and virtual. |
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| As the needle is moved farther from the mirror, the image moves towards the focus (but never beyond). Moreover, it gets progressively diminished in size. |
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