Why does a hollow double concave lens act as a diverging lens?

What happens when a hollow double concave lens is filled with different mediums and immersed in other mediums?

B) A hollow double concave lens acts as a diverging lens. When it is filled with a medium of higher refractive index than the surrounding, its diverging power increases. So if the lens is: A) Filled with air (n=1) and immersed in water (n=1.33) - Incorrect, air has lower refractive index than water B) Filled with water (n=1.33) and immersed in CS2 (n=1.6) - Correct, water has lower refractive index than CS2 C) Filled with air (n=1) and immersed in CS2 (n=1.6) - Incorrect, air has lower refractive index than CS2 D) Filled with CS2 (n=1.6) and immersed in water (n=1.33) - Incorrect, CS2 has higher refractive index than water Therefore, the lens will act as a diverging lens when filled with water and immersed in CS2, which is option B. The key is that the material inside the lens must have a lower refractive index than the surrounding medium to increase the diverging power of the concave lens.

Explanation:

A hollow double concave lens is made of thin glass and in the shape of a double concave lens. It can be filled with different mediums like air, water (refractive index 1.33), or CS2 (refractive index 1.6). When the lens is filled with a medium of higher refractive index than the surrounding, it acts as a diverging lens. Option A: Filled with air and immersed in water - Incorrect because air has a lower refractive index than water. Option B: Filled with water and immersed in CS2 - Correct because water has a lower refractive index than CS2, increasing the diverging power of the lens. Option C: Filled with air and immersed in CS2 - Incorrect because air has a lower refractive index than CS2. Option D: Filled with CS2 and immersed in water - Incorrect because CS2 has a higher refractive index than water. In conclusion, the key factor in determining the behavior of the hollow double concave lens is the refractive index of the medium inside the lens compared to the surrounding medium. By understanding this concept, we can predict whether the lens will act as a converging or diverging lens based on the refractive indices involved.
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