An object is placed at different distances, u, from a converging lens of focal length, 15.0cm. For what value of u does the lens act as a microscope?
u = 15cm only
u = 30cm only
M < 15cm only
u > 30cm only
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The correct answer is option C.
For a converging lens to act as a microscope, the object should be placed at a distance less than the focal length of the lens. In this case, the focal length of the lens is 15.0 cm. So, for the lens to function as a microscope, the object should be placed at a distance (u) from the lens that is less than 15.0 cm.
The correct answer is C. u < 15\text{ cm} only.
A converging lens acts as a microscope when the object is placed between the lens and its focal point. This is because the image formed by the lens is virtual, erect, and magnified. The magnification is given by the following equation:
M = \frac{v}{u}
where M is the magnification, v is the image distance, and u is the object distance.
The image distance is always negative for a virtual image, so the magnification is always positive. This means that the image is always magnified.
The magnification is greater than 1 when the object distance is less than the focal length. This is because the image distance is greater than the object distance when the object is placed between the lens and its focal point.
Therefore, the converging lens acts as a microscope when the object is placed between the lens and its focal point, or u < 15\text{ cm}.
A converging lens will produce magnified, virtual image when the object is placed within the focal length
A converging lens will produces magnified, virtual image when the object is placed within the focal length
