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Cause and Effect — From Light to Images
Luminous objects give out light
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Light travels straight
It moves in a straight line until something stops it.
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Opaque object blocks it
A dark shadow forms behind the object.
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Mirror reflects it
A mirror changes the light's direction and forms images.
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We see shadows, reflections, and images
Mind Map
Light: Shadows and Reflections
Chapter 11 · Class 7
11.1
Sources of Light
Luminous objects make light; non-luminous reflect it.
11.2
Straight Line
Light travels in a straight line.
11.3
Materials
Transparent, translucent, and opaque materials.
11.4
Shadows
Need light, an opaque object, and a screen.
11.5 & 11.6
Reflection & Images
Mirror image is erect and laterally inverted.
11.7 & 11.8
Pinhole & Items
Pinhole gives inverted image; periscope, kaleidoscope.
Key Terms and Definitions
- Luminous Object
- An object that emits its own light, like the Sun.
- Non-luminous Object
- An object that does not emit its own light, like the Moon.
- Transparent Material
- Lets light pass almost completely, like glass.
- Translucent Material
- Lets light pass partially, like tracing paper.
- Opaque Material
- Does not let light pass, like cardboard.
- Shadow
- The dark patch formed when an opaque object blocks light.
- Reflection of Light
- The change in the direction of light by a mirror.
- Plane Mirror
- A mirror that is flat and not curved.
- Image
- The likeness of an object that appears behind a mirror.
- Erect Image
- An image that is upright, the same way up as the object.
- Lateral Inversion
- The left-right reversal seen in a plane mirror image.
- Pinhole Camera
- A device that forms an inverted image through a tiny hole.
- Periscope
- A device with two mirrors to see hidden objects.
- Kaleidoscope
- A tube with three mirrors that makes changing patterns.
