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Question
A student used a device (X) to obtain/focus the image of a well illuminated distant building on a screen (S) as shown below in the diagram. Select the correct statement about the device (X).
Options
This device is a concave lens of focal length 8 cm.
This device is a convex mirror of focal length 8 cm.
This device is a convex lens of focal length 4 cm.
This device is a convex lens of focal length 8 cm.
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Solution
This device is a convex lens of focal length 8 cm.
Explanation:
The incident rays after passing through the lens converge at the focus. So, the device 'X' is a converging or a convex lens. The distance between the lens and the screen gives the focal length of the lens.
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