PPT: Light: Shadows and Reflections | PPTs for Class 7 PDF Download

 Page 1


Light - Shadows 
and Reflections
Page 2


Light - Shadows 
and Reflections
Introduction
What is Light?
Light is a fascinating 
phenomenon that allows 
us to see the world around 
us.
Importance
From fireflies to the Sun, 
light plays a crucial role in 
our lives.
Topics Covered
We'll explore light sources, 
behavior, shadows, 
reflection, and practical 
applications.
Page 3


Light - Shadows 
and Reflections
Introduction
What is Light?
Light is a fascinating 
phenomenon that allows 
us to see the world around 
us.
Importance
From fireflies to the Sun, 
light plays a crucial role in 
our lives.
Topics Covered
We'll explore light sources, 
behavior, shadows, 
reflection, and practical 
applications.
Sources of Light
Luminous Objects
Objects that emit their own 
light, like the Sun, stars, 
lightning, and fireflies.
Non-Luminous Objects
Objects that reflect light from 
luminous sources, like the 
Moon, planets, and mirrors.
Artificial Light
Human-made sources from 
early fire to modern LED 
lamps, which are energy-
efficient.
The Indian government promotes LED lamps to reduce electricity consumption. Proper disposal is 
essential to prevent environmental harm.
Page 4


Light - Shadows 
and Reflections
Introduction
What is Light?
Light is a fascinating 
phenomenon that allows 
us to see the world around 
us.
Importance
From fireflies to the Sun, 
light plays a crucial role in 
our lives.
Topics Covered
We'll explore light sources, 
behavior, shadows, 
reflection, and practical 
applications.
Sources of Light
Luminous Objects
Objects that emit their own 
light, like the Sun, stars, 
lightning, and fireflies.
Non-Luminous Objects
Objects that reflect light from 
luminous sources, like the 
Moon, planets, and mirrors.
Artificial Light
Human-made sources from 
early fire to modern LED 
lamps, which are energy-
efficient.
The Indian government promotes LED lamps to reduce electricity consumption. Proper disposal is 
essential to prevent environmental harm.
Does Light Travel in a Straight Line?
Aligned Holes
Light creates a bright spot when 
passing through aligned holes in a 
straight line.
Misaligned Holes
No spot appears when holes are 
misaligned, showing light doesn't 
bend around obstacles.
Straight Pipe Test
A candle flame is visible through a 
straight pipe but not a bent one.
This property is known as rectilinear propagation. Light can bend under specific conditions, but typically travels in 
straight lines.
Page 5


Light - Shadows 
and Reflections
Introduction
What is Light?
Light is a fascinating 
phenomenon that allows 
us to see the world around 
us.
Importance
From fireflies to the Sun, 
light plays a crucial role in 
our lives.
Topics Covered
We'll explore light sources, 
behavior, shadows, 
reflection, and practical 
applications.
Sources of Light
Luminous Objects
Objects that emit their own 
light, like the Sun, stars, 
lightning, and fireflies.
Non-Luminous Objects
Objects that reflect light from 
luminous sources, like the 
Moon, planets, and mirrors.
Artificial Light
Human-made sources from 
early fire to modern LED 
lamps, which are energy-
efficient.
The Indian government promotes LED lamps to reduce electricity consumption. Proper disposal is 
essential to prevent environmental harm.
Does Light Travel in a Straight Line?
Aligned Holes
Light creates a bright spot when 
passing through aligned holes in a 
straight line.
Misaligned Holes
No spot appears when holes are 
misaligned, showing light doesn't 
bend around obstacles.
Straight Pipe Test
A candle flame is visible through a 
straight pipe but not a bent one.
This property is known as rectilinear propagation. Light can bend under specific conditions, but typically travels in 
straight lines.
Light Through Different 
Materials
Transparent
Materials like glass allow light 
to pass through completely. 
Objects behind are clearly 
visible.
These may create faint 
shadows.
Translucent
Materials like frosted glass 
allow partial light passage. 
Objects appear blurred.
These form lighter shadows 
than opaque materials.
Opaque
Materials like cardboard block light completely. No visibility 
through them.
These form the darkest shadows.