Question Video: Determining the Materials Concave Lenses Can be Made From | Nagwa Question Video: Determining the Materials Concave Lenses Can be Made From | Nagwa

# Question Video: Determining the Materials Concave Lenses Can be Made From Science • Third Year of Preparatory School

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Which of the following materials could a concave lens be made of? [A] Wood [B] Glass [C] Copper [D] Steel [E] Concrete

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### Video Transcript

Which of the following materials could a concave lens be made of? (A) Wood, (B) glass, (C) copper, (D) steel, (E) concrete.

Let’s first remember that a lens is a piece of transparent material with a particular shape that can be used to change the direction that light rays are traveling in. A transparent material is one that allows light to pass through it. In other words, it is see-through. So the material we are looking for must be see-through and let rays of light pass through it.

To answer this question, we can look at the options we have been given and decide which of these materials are transparent. We know that wood is not transparent. We wouldn’t expect to be able to see through a tree, for example. So (A) cannot be the correct answer. Similarly, metals like copper or steel aren’t transparent. We wouldn’t expect to be able to see through a copper coin or a steel saucepan. So neither option (C) nor option (D) can be correct. Concrete is also not transparent. We know that we can’t see through concrete walls, for example. So (E) cannot be the correct answer.

Glass, however, is transparent. We know that light can pass through things like glass windows, which are used to let sunlight into buildings and allow us to see outside. So glass is the only transparent material in this list. All the other materials are opaque, which means they don’t let light travel through them. Glass is the only material on the list that we could make a concave lens out of, or any other lens for that matter. So the correct answer then is option (B), glass.

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