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WAEC Physics 2022 Paper

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Question : 14

Total: 50

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

Solution:

Concept:

For a converging lens to act as a simple microscope, the object must be placed within the focal length.

Explanation:

A converging lens behaves like a magnifying glass when the object distance is less than the focal length.

This produces a virtual, erect, and magnified image on the same side as the object.

Given focal length,

f = 15.0 \, \text{cm}

.

Therefore, the lens acts as a microscope when

u < 15.0 \, \text{cm}

.

Answer:

C.

u < 15 \, \text{cm}

only

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