primary...night and day
Don’t be kept in the dark any longer
all you need is
• Torch
• Wall
• Darkened room
1. Find a darkened room, switch your torch on and point it at a wall. You’ll notice that the beam of light from the torch travels in a straight line. All light rays travel in straight lines, unless they meet an object, and at a very fast speed indeed.
2. Now put your hand in front of the torch. You’ll see a shadow of your hand appear on the wall. If you put something solid in the way of a beam of light , it makes a shadow. A shadow is a dark area where light cannot reach.
3. Move your torch closer to your hand. As you move your torch closer, more light is blocked and the shadow gets bigger.
science
When light rays hit an object in their path, they pass right through, bounce off or are absorbed. It all depends on what the object is made of. Materials like glass let light through and are called transparent. Materials that stop light passing through are called opaque. When light hits an opaque object, it casts a shadow.
Day and night are really just light and shadow. The Earth is spinning on its axis as it travels around the Sun. At any one time, half of the Earth faces the Sun. On this half of the Earth it is daytime. The other half of the Earth is in the shadow of the Earth cast by the Earth getting in the way of the light from the sun. Here it is night-time.
The Sun is our main source of light. There would be no plants and the world would be very cold if there was no Sun. It is a natural source of light. Your desk lamp, on the other hand, is an artificial source of light.
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