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.
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.
A LONGER WAVE LENGTH IS ASSOCIATED WITH A HIGHER/LOWER FREQUENCY.
A LONGER WAVE LENGTH IS ASSOCIATED WITH A LOWER FREQUENCY.
ORDER OF THE SPECTRUM
- RADIO WAVES
- MICRO WAVES
- INFRA-RED WAVES
- VISABLE LIGHT
- ULTRA VIOLET
- GAMMA RAYS
- 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.
What is INDUCED current?
The current obtained due to the relative motion between the coil and the magnet is called induced current.
The electromagnetic waves consists of two perpendicular fields: ___, ____.
- Electric field
- Magnetic Field
All wave lengths have the same...
- Re-emission: light reflected back from a surface
- opp of Absorption
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.
Most tihngs around us are ___. Meaning, they absorb light without remission (reflecting).
Energetic vibrations does what to thermal energy?
Increase temp. of material
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.
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
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
- reflecting surfaces are irregular, light is returned in irregular directions
- rough surface
- most of our env. seen by this kind
UNLESS LIGHT IS PERP. TO THE SURFACE OF PENETRATION, BENDING OCCURS
COLOR WITH LOWEST FREQ.
AND WITH HIGHEST
PRODUCE AND DISCHARGE, MAKE
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.
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.
The serperation of light into colors arranged by frequency.
The alignment of the transverse electric vectors that make up electromagnetic radiation. Such waves of aligned vibrations are said to be polarized.
- Gamma rays: They have very high
- energy and will even go through metals.
SPECIFIES THE NUMBER OF TO AND FRO VIBRATIONS IT MAKES IN A GIVEN TIME (USUALLY 1 SEC)
The frequency of virbating electrons and the frequency of the wave produced are...
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.
Refraction rather than reflection
- Light rays
- are bent to produce a displaced image of distant objects or the sky.