ENERGY: EM Spectrum

ENERGY: EM Spectrum

Electromagnetic Radiation

What is LIGHT

• It is a way scientists describe and study types of energy

  
  

• It is a 'spectrum' or range of energies that help us understand the universe

• It is NOT just the energy visible to humans

ALL Light Energy moves at the SAME SPEED in a vacuum. (3 x 10⁸ m/sec)

There is a relationship between the characteristics of wavelength, energy and frequency......

Multiple Choice

Which type of EM wave has the LONGEST wavelength?

• gamma

• microwave

• visible

• radio

Multiple Choice

Which type of EM wave has the highest frequency?

• radio

• infrared

• x-ray

• gamma

How does Light Radiate?

• It radiates (moves from the source) in ALL directions.

• The energy is most concentrated at the source (where it starts)

• As it spreads out, it "dissipates"

• The intensity of the light to an observer from a source is inversely proportional to the square of the distance from the observer to the source.

• So, if you double the distance from the source of energy, the intensity of the energy is 1/4th.

Multiple Choice

Visible light leaves a flashlight. You observe this energy from a distance of 4 feet. How much less intense is the light when it reaches your eyes?

• 1/2

• 1/8

• 1/16th

• the same intensity as if I was right next to the flashlight

EM Energy can be studied and measured

• all waves start with a 'disturbance'

• the energy in all LIGHT waves can travel through the vacuum of space

• Light energy can interact with matter

• Light waves can be measured to have a wavelength (distance)

• Light waves can have a frequency (how many waves pass by a point in 1 second= 1 Hz of frequency)

• Light waves also have a period (the time it takes for a wave to pass)

• Light waves can act like 'particles' (ie they can reflect, refract and diffract as well as add together, or be constructive or have destructive interference).

In the thermal unit, we explored:

1. The impact of the ANGLE of visible light on absorption

2. WHAT the material visible light is directed on matters (based on its specific heat)

3. TEXTURE /surface impacts how visible light interacts

4. COLOR

Multiple Choice

Which surface feature reflects the most Visible LIGHT energy?

• red

• black

• yellow

• white

Multiple Choice

Which angle results in the highest intensity of light waves upon an object?

• 0 degrees

• 20 degrees

• 90 degrees

• 45 degrees

Multiple Choice

Which will result in the LEAST amount of energy being absorbed ?

• a dark, rough surface

• a white, rough surface

• a shiny, flat, silver surface

• a shiny rough surface

ALL wavelengths of EM waves (aka "LIGHT") are used in Science

In astronomy, ALL of the theories are based upon current understanding of the speed of light and types of EM waves.

This image shows the different types of equipment NASA has used to study the universe