Question

A converging lens and a converging mirror have the same focal length in air.

Part A Which one has a longer focal length if they are used underwater? Construct the correct explanation. Drag the terms on the left to the appropriate blanks on the right to complete the sentences. In the case of the mirror, the convergence of light rays is achieved through BLANK, which BLANK on the indices of refraction. For the lens, however, convergence is achieved through BLANK, which BLANK on the indices of refraction. As the difference in the indices of refraction becomes BLANK, refraction itself becomes less pronounced. So when air is swapped for water, the rays will be bent at BLANK angles and the focal point will be BLANK from the lens. Since the focal length of the mirror BLANK change, the lens will have a BLANK focal length under water. Choices for the BLANKs further from will not refraction closer to greater does not depend reflection less will depends

Answer 1

In the case of the mirror, the convergence of light raya is achieved through reflection, which does not depends on the indices of refraction.

For the lens, however convergence is achieved through refraction, which depends on the indices of refraction.

As the difference in the indices of refraction becomes less, refraction itself becomes less pronounced.

So when air is swapped for water, the rays will be bent at less angles and the focal point will be further from the lens.

Since the focal length of mirror will not change, the lens will have a greater focal length under water.

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