GK
PHYSICS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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7.5 cm on the near side
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30 cm on the near side
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15 cm on the near side
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7.5 cm on the far side
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Detailed explanation-1: -It is a converging lens. A diverging lens has a focal length of 10 cm. Where is the image located when an object is placed 30 cm from the lens? 15 cm on the near side.
Detailed explanation-2: -When an object is placed at 10 cm and 30 cm from a convex lens, images obtained are of the same magnitude of magnification. The focal length of the lens may be: 1. 10 cm.
Detailed explanation-3: -v=−30cmf=+10cmu=? So from lens formula 1v−1u=1fWe get, 1−30−1u=110or 1u=−110−130⇒1u=−430or u=−7.5 cmSo, the object must be placed in front of the lens at a distance of 7.5 cm from it.
Detailed explanation-4: -Here u is the distance of the image from the optical centre. Substitute f=−30cm and v=−15cm to find the value of u. Substitute, v=−15cm, u=−30cm and h1=5cm to find the value of h2. Therefore, the object should be placed 30 cm from the optical centre and the size of the image formed is 2.5 cm.
Detailed explanation-5: -The object should be placed at a distance of 5 cm in front of convex lens.