Here is the completed worksheet with explanations for each answer:
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1. Light travels in `straight` lines.
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Explanation: This is a fundamental principle of geometric optics. In a uniform medium (like air, water, or vacuum), light travels in straight-line paths called rays. This is why we see sharp shadows and can use lasers for precise alignment.
2. `Reflection` is when light bounces off an object.
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Explanation: Reflection is the change in direction of a wavefront at an interface between two different media so that the wavefront returns into the medium from which it originated. When light hits a surface and "bounces" back, this is reflection.
3. Light reflects from a smooth surface (mirror, glass, polished metal) at the `same` angle as it hits the surface.
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Explanation: This describes the Law of Reflection. The angle of incidence (the angle between the incoming ray and the normal/perpendicular to the surface) is equal to the angle of reflection (the angle between the reflected ray and the normal). This is why mirrors produce clear, undistorted images.
4. For a smooth surface, reflected light rays travel in the `same` direction.
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Explanation: Because the surface is flat and even, all parallel incident rays will reflect at the same angle relative to the normal. This results in the reflected rays remaining parallel to each other, traveling in the same overall direction. This is called specular reflection.
5. For a rough surface, (leather, stone, fabric) reflected light rays scatter in `many` directions.
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Explanation: A rough surface has many tiny, randomly oriented facets. Each facet reflects light according to the law of reflection, but because the facets point in different directions, the reflected rays scatter in many different directions. This is called diffuse reflection, which is why you don't see a clear image in these materials.
6. Which diagram shows a smooth surface? `Diagram A`
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Explanation:
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Diagram A shows parallel incident rays hitting a flat, even surface. The reflected rays are also parallel and travel in the same direction. This is characteristic of a smooth surface (specular reflection).
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Diagram B shows parallel incident rays hitting a bumpy, uneven surface. The reflected rays scatter in many different directions. This is characteristic of a rough surface (diffuse reflection).
7. Light intensity is measured with a device called a `light meter` (or photometer).
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Explanation: A light meter (or photometer) is an instrument used to measure the intensity or illuminance of light. It quantifies how much light falls on a surface (illuminance, often measured in lux or foot-candles) or the brightness of a light source itself (luminance).
8. Give an example of a dim light: `Candle flame` (or night light, starlight, flashlight on low setting, etc.)
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Explanation: A dim light emits relatively little visible light energy per unit area. A candle flame is a classic example of a low-intensity light source compared to most artificial lights.
9. Give an example of a bright light: `Sun` (or car headlight, stadium floodlight, LED flashlight on high, etc.)
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Explanation: A bright light emits a large amount of visible light energy per unit area. The Sun is the brightest natural light source we experience daily. Artificial examples include powerful lamps or headlights.
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Parent Tip: Review the logic above to help your child master the concept of light reflection worksheet.
