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Investigating how different materials allow light to pass through them in different ways.
Have you ever wondered why you can see the sun through a window, but only a soft glow through a lampshade, and absolutely nothing through a closed door?
Transparent materials are like open gates for light. They allow almost of light rays to pass through them without scattering. Because the light travels in straight lines through these materials, we can see objects on the other side very clearly. Common examples include clear glass, clean water, and air. If you are wearing glasses right now, you are looking through a transparent material designed to help you see the world without any blurriness!
Imagine a clear glass window. 1. Light from the sun hits the glass. 2. The light passes straight through to the other side. 3. You can see the trees and birds outside perfectly because the light rays didn't change direction.
Quick Check
If you can see a fish clearly at the bottom of a lake, is the water transparent, translucent, or opaque?
Answer
Transparent
Translucent materials are a bit more mysterious. They allow some light to pass through, but they scatter the rays in many different directions. This means you can see light coming through, but you cannot see a clear image of what is on the other side. It looks blurry or fuzzy. Think of a frosted bathroom window or a piece of wax paper. These materials are perfect when you want light to enter a room but still want some privacy.
Consider a pair of tinted sunglasses or a frosted shower curtain. 1. Light hits the material. 2. Some light is absorbed, and the rest is scattered as it passes through. 3. You see a 'glow' or a 'shape,' but you cannot read a book held behind it.
Quick Check
Why would a lightbulb be made of frosted (translucent) glass instead of clear glass?
Answer
To scatter the light so it isn't too bright or 'harsh' for your eyes.
Opaque materials are the ultimate light stoppers. They do not let any light pass through them. Instead, they either reflect the light (bounce it off) or absorb it (turn it into heat). Because no light gets through, you cannot see anything on the other side. This is why opaque objects create shadows. A shadow is simply an area where light was blocked by an opaque object. Common examples include wood, metal, and your own body!
Imagine you are standing in front of a flashlight against a wall. 1. Your body is an opaque object. 2. The light hits your back but cannot pass through to the wall. 3. The area on the wall directly behind you remains dark, forming a shadow that is the same shape as you.
Which material would be best for a car's windshield?
What happens to light when it hits a piece of cardboard?
Tissue paper is an example of a translucent material.
Review Tomorrow
Tomorrow morning, look around your kitchen. Can you find one transparent, one translucent, and one opaque object?
Practice Activity
Take a flashlight and shine it through different items in your house (a cereal box, a plastic bag, a glass of milk). Classify each one based on how much light reaches the wall!