Light Shadows and Reflections Class 7 Notes

Light Shadows and Reflections Class 7 Notes

Light Shadows and Reflections Class 7 Notes

1. Flashing: Brief and sudden bright light.
2. Luminous: Objects that emit their own light.
3. Substantial: Considerable importance, size, or worth.
4. Shadow: The dark patch, where light does not reach
5. Reflection of light: Change in direction of light by a mirror.
6. Perpendicular: Exactly vertical or upright or forming a right angle with each other.
7. Erect: An upright image.
8. Perceived: To become aware of, know.
9. Lateral inversion: The left-right reversal, i.e., the left appears right in an image and right appears left in the image.
10. Periscope: An instrument to get a view/see the objects above the surface
11. Kaleidoscope: An optical toy consisting of two or more mirrors at particular angles.

1. Light: A form of energy

Properties:

1. Travels in straight lines.
2. Can be reflected, refracted, or absorbed by different materials.

2. Types of Materials:

(i) Transparent Materials

Examples: Clear glass, water.

(ii) Translucent Materials

Examples: Frosted glass, wax paper.

(iii) Opaque Materials

Examples: Wood, metal.

3. Shadows

Characteristics:

1. Opaque objects create darker shadows.
2. Translucent objects create lighter shadows.
3. Some transparent objects can create faint shadows.

Formation:

1. Requires a light source, an opaque object. and a screen.
2. The shape, size, and sharpness of a shadow depend on the object's position relative to the light source and the screen.

4. Reflection of Light

Images Formed by Mirrors:

1. Same size as the object.
2. Erect (upright).
3. Cannot be obtained on a screen.
4. Laterally inverted (left and right are reversed).

5. Luminous and Non-luminous Objects

1. Luminous Objects
2. Examples: Sun, stars, fireflies.
3. Non-luminous Objects
4. Examples: Moon, planets.

6. Applications of Light and Shadows

1. Use in art forms like shadow puppetry.
2. Practical applications in photography, design, and visual arts.