Light Energy Flashcards
Light does not require a __________ to travel
Medium
Any object that produces light is known _____________
Source of light
What are the two types of light sources?
Natural light source and artificial light source
What is natural light source? Give an example
Natural light source exist in nature on their own. Ex: sun
What is artificial light source? Give an example
Light sires that are man made. Ex: candles, electric bulbs
What is a luminous object?
Objects that give out light of their own are called luminous objects
What are non-luminous objects?
Objects that do not give out light of their own are called non-luminous object
What is bioluminescence
The production of light by a living organism as a result of some chemical energy getting converted into light energy is called bioluminescence
Give examples of bioluminescent objects
Fire flies, jellyfish
Why is moon a non-luminous object? Give reason
Moon does not have any light of its own. It’s light is refracted from the sun
What are greenhouses
Structures built with glass or transparent plastic for growing plants
What is a transparent medium? Give examples
A medium that allows most of the light to pass through it is called transparent medium. Ex: clear glass, Clear water
What is translucent medium? Give examples
A medium that allows only a part of the light to pass through it is called translucent medium. Ex: butter paper, fog
What is opaque medium? Give examples
A medium that does not allow any light to pass through it is called an opaque medium
Define rectilinear propagation of light
The property of light travelling in straight lines in a medium Is called the rectilinear propagation of light
What do you mean by principle of least time?
Light takes a path that requires the shortest time is called the principle of least time
What is ray of light?
It is a path along which light energy travels
What is beam of light? What are it classifications?
A group of rays of light is called a beam of light. A beam of light is classified into 3 types namely; parallel, convergent, divergent.
What is parallel beam of light?
A group of parallel rays of light is called parallel beam of light
What is convergent beam of light?
When rays of light from different directions converge at a point, the collection of rays is called a convergent beam of light
What is a divergent beam of light?
When rays of light from a point diverge in different directions, this collection of rays is called a divergent beam light
What is the speed of light?
3 x 10 to the power of 8 m/s
Explain the formation of shadows
When the light rays are stopped by an object, a dark region forms behind the object, this dark region is called a shadow
What are the characteristics of shadows?
- Formed only in the presence of light
- Always formed on the source of light
What does the position of the shadow depend on?
It depend on the size one position of both the object and the light source
What is an umbra?
The darkest part where no light falls at all is called the umbra
What is a penumbra?
It is the region of partial darkness
