The Earth's biggest source of light is Sun. Heat and light energy by sun created by the sun travels through space in straight lines called rays at almost 187,000 miles per second. The Earth's spins around once a day, changing which part of globe gets sunlight. This creates day and night. Other things that radiate, or give off, light include electric lightbulbs, candles, and television sets.
What are shadows?
Shadows happen in places where an object
Stops light from getting through. Materials that light shines through fully are called transparent. Translucent materials only let a little light through. Opaque material don't let any light through at all. The shape of the shadow depends on the object blocking the light. If an object is moved closer to a light source, it's shadow gets bigger because it blocks more light rays.
Why do mirror reflect images?
All surfaces reflect light but if they are bumpy, the light rays are reflected in all directions. Mirrors are made from very smooth surfaces that reflect the rays back in the same pattern as they hit it, creating a clear image of any object. Words reflected in a mirror appear back to front, as if they were facing away from us and we were looking through the page.
How do periscopes work?
Periscopes are devices that use reflecting mirrors in order to see things from a lower level. An Angled mirror reflects an image, made up of light, down a tube. A second mirror at the bottom of the tube reflects the light again to turn the image back the right way up. Periscopes are often used to see surface ships from underwater submarines, or to see over people's heads in crowds.
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