# ECOL 1000 Lecture Notes - Lecture 1: Radiant Energy, Electromagnetic Spectrum, Kinetic Energy

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8 Feb 2017
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ENERGY is the ability or capacity to do work on some form of matter.
Potential energy is the energy of an object prior to it being released
as free energy, commonly called the energy at rest.
Kinetic energy is the free energy of motion or action.
Heat energy is kinetic energy generated by the motion of molecules. it is measured as the sum total of
all molecular motion in an object.
Radiant energy is the energy transferred and electromagnetic waves by all objects with a
temperature >0K (kalvins)(-273C (celcious) or absolute zero)
Energy follows the Laws of Thermodynamics:
First Law of Thermodynamics: In all physical & chemical changes,
energy is neither created nor destroyed, but it may be converted
from one form to another. (Law of Conservation of Energy)
Second Law of Thermodynamics: When energy is changed from one
form to another, some of the useful energy is always degraded to
lower-quality, more dispersed, less useful energy.
** Properties of Radiant Energy or Radiation:
* Light, heat, radio, X-rays, etc. are all part of the
electromagnetic spectrum or radiation.
* all objects with a temperature above 0K emit radiation
* the amount of energy emitted by an object and the wavelength at which it is emitted is
dependent on the temperature of the object.
(the hotter the object the shorter the wavelength)
** As stated in the Stefan-Boltzmann Law:
* hotter objects (blackbodies) emit more energy than cooler objects,
and the intensity of energy radiated increases according to the fourth
power of its absolute T°.
I = σT4
I = intensity of radiation in watts per square meter
σ = a constant, 5.67 x 10-8 watts per square meter K4
T = temperature of the body in °Kelvin
EX: Using this formula we can calculate that the Earth emits about
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