Electromagnetic Energy

Topic 5 Energy in Earth Processes

energy  The ability to do work

Electromagnetic energy  The type of energy given off in transverse waves by all matter above absolute zero  Each kind of e-mag energy has its own wavelength

wavelength

Electromagnetic spectrum  A model showing all the forms of e-mag energy

 Page 14 ESRT  Visible light can be broken down into colors by wavelength.

The hotter the object the more e-mag energy it gives off.

high low cold hot Temperature of Object

The hotter the object, the shorter the wavelength given off.

long short cold hot Temperature of Object

refracted E-mag waves can be scattered absorbed reflected transmitted

The characteristics of a surface determine the amount and kind of e-mag energy absorbed.

 Color - dark absorb more/reflect less  Texture (rough/smooth) - rough absorbs more  Luster/reflectivity (shiny/dull) - dull absorbs more

source  Region with a higher concentration of energy than its surroundings

Sink (no, not the kitchen kind)  Region with a lower energy concentration than its surroundings  Energy always flows from a source to sink.

* Energy is transferred across interfaces.

source sink 50°C 30°C

The source radiates more than it absorbs.

*temperature decreases* The sink absorbs more than it radiates.

*temperature increases*

* Energy is transferred across interfaces.

40°C 40°C

The 2 objects absorb the same amount that they radiate.

* temperature is constant* This is called dynamic equilibrium balance .

or radiative

Energy Transformations  When e-mag energy of short wavelength is absorbed, it can be reradiated at longer wavelengths.

 A material that is a good absorber of electromagnetic energy is a good radiator of electromagnetic energy.