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What is the electromagnetic spectrum?
The classification of electromagnetic waves acccording to frequency. (In a vacuum, all electromagnetic waeves move move at the same speed differing only in frequency.
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What are electromagnetic waves?
What are they made of?
- A larger group of energy.
- It is the vibrating electric and magnetic fields that are regenerating each other to make up an electro.wave.
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A LONGER WAVE LENGTH IS ASSOCIATED WITH A HIGHER/LOWER FREQUENCY.
A LONGER WAVE LENGTH IS ASSOCIATED WITH A LOWER FREQUENCY.
LONGER-LOWER
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ORDER OF THE SPECTRUM
- RADIO WAVES
- MICRO WAVES
- INFRA-RED WAVES
- VISABLE LIGHT
- ULTRA VIOLET
- XRAYS
- GAMMA RAYS
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ELECTROMAGNETIC INDUCTION
- Def1: The induction of voltage when a magnetic field changes with time. If the magnetic field within a closed loop changes in any way, a voltage is induced in the loop.
- Def2: The phenomenom by which a current is induced in a conductor due to change in the magnetic field near the conductor is known as electromagnetic induction.
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What is INDUCED current?
The current obtained due to the relative motion between the coil and the magnet is called induced current.
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Electromagnetic induction.
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The electromagnetic waves consists of two perpendicular fields: ___, ____.
- Electric field
- Magnetic Field
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All wave lengths have the same...
speed
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Reemision Defintion
Absoprtion def
- Re-emission: light reflected back from a surface
- opp of Absorption
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What happens to the electrons and their energy when light is reemitted (reflected)?
- The atoms or molecules in the material holds the energy for less time, with less change of collision w/ neighboring atoms and molecules.
- Less energy is trtansformed as heat.
- Instead, energy is wasted on light remission.
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Most tihngs around us are ___. Meaning, they absorb light without remission (reflecting).
OPAQUE
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Energetic vibrations does what to thermal energy?
Increase temp. of material
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Why are metals shiny?
- Metals have loose free outer electrons.
- When light sines on metal and set these free electrons into vibration, their energy does not "spring" from atom to atom--it is reflected instead.
- With each bounce, comes absorption.
- On dry surfaces, it bounces right back to the eye. Whearas in wet surfaces, more is absorped.
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What is reflection?
- The return of light rays from a surface
- Energized electrons re-emit the light we see on each page.
- White- reemits all visible frequencies
- Black- Absorbs all visible frequencies
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law of reflection
how do you measure
the angle of reflection equals the angle oc incidence (pool table).
measure them from a perpendicular line to the plane of the relfecting surface
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diffuse reflection
- reflecting surfaces are irregular, light is returned in irregular directions
- rough surface
- most of our env. seen by this kind
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REFRACTION
UNLESS LIGHT IS PERP. TO THE SURFACE OF PENETRATION, BENDING OCCURS
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COLOR WITH LOWEST FREQ.
AND WITH HIGHEST
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EMITTING
PRODUCE AND DISCHARGE, MAKE
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Why do objects seem a certain color?
Objects around us reflect only part of the light that is incident upon them, thae part that provides their color
Ex A red rose has the ability to reflect red light but cannot reflect other colors.
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PIGMENTS
fine particles that selectively absorb light of particular frequencies and selectively transmit others.
- Transmission: If the object is transparent, then the
- vibrations of the electrons are passed on to neighboring
- atoms through the bulk of the material and reemitted on the
- opposite side of the object.
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DISPERSION DEF
The serperation of light into colors arranged by frequency. 
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Polarization
The alignment of the transverse electric vectors that make up electromagnetic radiation. Such waves of aligned vibrations are said to be polarized.
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- Gamma rays: They have very high
- energy and will even go through metals.
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FREQUENCY
SPECIFIES THE NUMBER OF TO AND FRO VIBRATIONS IT MAKES IN A GIVEN TIME (USUALLY 1 SEC)
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The frequency of virbating electrons and the frequency of the wave produced are...
the same
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What is a mirage?
- A mirage is a naturally occurring optical
- phenomenon in which light rays are bent to produce a displaced image.
- Light travels faster through the thinner hot air near the surace than through the denser cool air above. The result is upward bending.
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Refraction rather than reflection
- Light rays
- are bent to produce a displaced image of distant objects or the sky.
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