Download Class 12 Optics

Class 12 Optics
The Study of light and it’s behaviour
Jake Smythe 2009
Contents:
1. Page 1
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Introduction
Optical Terms
Light Sources
Expt.1 Visibility of light
2. Page 2
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Optical Illusions
The Ritchie Photometer
The Inverse Square Law
Candle Luminescence
A5 covering an A3 sheet
Photometric Units
3.
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Speed of Light
What Is Light?
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Expt.5 refraction
Total Internal Reflection
Expt.6 Reflection
Convex Mirrors
Concave Mirrors
Plane Mirrors
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Expt.7 Shadows
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Expt.8 Colours
4.
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Introduction:
Optics is the study of light; it’s origin, propagation, properties, and behaviours. A
leading branch of physics, optical inventions opened up possibilities for many other
branches of physics and science (medicine, telescopes, microscopes etc).
Optics itself is divided into two disciplines:
1. Classical (geometrical) optics, or how light behaves, or
2. Quantum optics, what light is made of
But a few of the modern optical inventions are: laser, GPS, etc, etc
Optical Terms:
Transparent: light passes through a substance without any (visible) effect.
Translucent: light passes through a substance, but is scattered.
Reflection: light is bounced back.
Deflection: light is bounced back, but also scattered.
Opaque: light can’t pass through a substance.
Absorption: light is captured by the surface of a substance
Partial Absorption: surfaces appear in a particular colour
Light Sources:
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Combustion (chemical energy)
Nuclear Fission/Fusion
Electricity
Chemiluminescence (chemical energy (cold))
Experiment. 1 Visibility of Light
Method:
A laser rig (see below picture) is set up where the light is bouncing between mirrors
placed on either wall, and at the top so that the laser beam is reflected back upon itself.
To view the light, water or chalk dust were sprayed over where the light was passing.
Observation:
When there was nothing being sprayed into the path of the light it was invisible to us, it
only became visible when it was reflected. The second observation stems from the light
being reflected through itself at the top, and the lack of any effect. From this we were
able to conclude:
1. Light itself is invisible; we can only perceive it when it is reflected of deflected by
a substance, or when it enters the eye.
2. Light travels in straight lines.
3. Light rays cross each other without affecting each other (light acting like a wave,
not a particle).
Image courtesy of Elwin Burger.