Page 1 - Lesson Notes- Types of object and rectilinear propagation
P. 1
SAI INTERNATIONAL SCHOOL
Class 6
Lesson Notes
Subject- Physics
Ch. – Light, Shadows and Reflection
Subtopic- Transparent, Translucent and Opaque;
Rectilinear propagation of light
NOTES:
A substance through which light propagates, act as medium.
Different materials can be broadly categorized into three types-
1. transparent
2. translucent
3. Opaque materials.
Materials through which light can pass completely are called transparent
materials. For e.g. air, water, glass etc.
Materials through which light can propagate partially are known as translucent
materials. For e.g. frosted glass, butter paper etc.
Materials through which light cannot propagate are known as opaque materials.
For e.g. wall, wood, stone etc.
Rectilinear propagation of light.
The property of light that it travels in a straight line is known as rectilinear
propagation of light.
A narrow group of light rays considered as a beam.
l In a beam of light from a small source, the rays are moving away from each
other. Such rays are called divergent rays.
l In a beam of light from a very large source which is located far away, the rays of
light is taken as parallel to each other.
l When rays of light meet at a common point, they are called convergent rays.
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