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Science_Lab_Yellow / Lesson 6: Light Passes Through

Light Passes Through

What will we be learning today?

  • In this lesson, we are going to learn all about what can light pass through.

  • What Can Light Pass Through?

    Sometimes when light strikes matter, almost all the light gets through. Sometimes only some light gets through. Sometimes none of it gets through.


    Opaque materials completely block light from passing through.

    Transparent materials allow light to pass through with almost no disturbance. Transparent materials may or may not color the light, but you can see objects clearly through them

    Translucent materials allow only part of the light to pass through, while also bouncing it in many new directions. Since translucent materials give only a blurry view, they are often used in shower doors. They let some light in, but provide privacy.


    Which objects in this scene are transparent? Translucent? Opaque?


    You might think empty space is opaque to light. After all, light and sound are both waves, and sound waves do need some kind of matter to travel through. However, as the starry night sky shows, light can travel through empty space.


    Light from celestial objects, such as this galaxy, passes through empty space to reach us.


    Controlling Light

    In our daily lives, we use many products to control light. You may be familiar with some of the products.


    One of the most interesting ways for controlling light depends on polarization (poh luhr uh ZAY shuhn). Light travels in waves. Normally these waves vibrate in all directions. However, light can be polarized by some materials. That is, only one direction of light vibrations can pass through them.


    One of the most interesting ways for controlling light depends on polarization (poh luhr uh ZAY shuhn). Light travels in waves. Normally these waves vibrate in all directions. However, light can be polarized by some materials. That is, only one direction of light vibrations can pass through them.


    This reflected light is often naturally polarized to vibrate sideways. Polarizing materials in sunglasses, however, let through only the light that is vibrating up and down. This blocks glare and all other kinds of light that vibrates sideways.


    Scientists have also developed sunglasses that change color by themselves! They turn dark in the sunlight but lighten indoors. The lenses of self-tinting glasses contain very small amounts of a transparent, silver-containing chemical. When struck by bright light, this chemical turns into tiny silver particles. These particles block light and darken the glass.





    Self-tinting glasses indoors




    Outside in bright light


    When taken indoors, the silver particles become transparent again, so the lenses automatically lighten.


    Let's Review What We Learned Today!

  • Now complete your PDA!