Integrated Coordinated Science for the 21st Century
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Answers
Physics To Go
- When an object blocks light from hitting part of a screen, the result is a shadow.
- The shadow becomes larger when light can spread out more after it passes the object. Light can spread out more when the screen is moved away from the light, the object is moved toward the light, or the light is moved toward the object.
- The halo is a region of intermediate brightness at the edge of the shadow. The effect is to make the shadow edge appear fuzzy. The gray halo occurs when the light bulb is frosted (an “extended source”). Since the light comes from different places on the bulb, the area at the edge of the shadow is illuminated by light from only part of the bulb.
- The length of the shadow is determined by the altitude of the Sun (the angle between the horizon and the Sun). Since the light rays of sunlight are approximately parallel, the orientation of your body and also the orientation of the ground determine the length of the shadow.
- Because the Sun, although quite large, is so very far away.
- a) Where all three lights overlap, in the center, you see white. Where red and green overlap, you see yellow. Where red and blue overlap, you see purple. Where blue and green overlap, you see blue-green.
b) The central region is the brightest. Three regions with two overlapping lights (yellow, blue-green, and purple) are the next brightest. The red, blue, and green regions are the least bright.
- a - b) See drawing on p. 244. The rest of the screen is red.
c) See drawings on previous pages.
- Answers will vary.
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