The Nature of Light:

Objectives:

    1.    Describe the dual-nature of an electromagnetic wave.

    2.    Describe the relationship between visible light, radio waves, microwaves, and X-rays.

Key Terms:

    electromagnetic spectrum    electromagnetic wave    infrared    ultraviolet    light-year

Resources:

Notes:

Nature of Light:

Light Energy:

Light is energy.  Light is also an electromagnetic wave.  Electromagnetic waves are named so because the consist of two waves. One part electric and the other magnetic.  Most electromagnetic waves are the result of excited electrons surrounding the nuclei of atoms. 

• When an atom absorbs electricity its electrons (e-) become excited
• The excited e- jumps to higher energy orbits
• As the excited e- looses energy, it falls back to its original orbit and releases a photon.
• A photon is a tiny packet or bundle of energy that contains the exact amount of energy that the atom absorbed.

·        The amount of energy a photon contains determines what type of light is emitted

(www.yorku.ca)

Electromagnetic Waves: (Light)

The above chart is called the electromagnetic spectrum.  In the center is the visible light spectrum. 

• All forms of electromagnetic radiation travel at 3x10⁸ m/s in a vacuum

• Electromagnetic waves require no medium

• All electromagnetic waves are transverse waves

• 2 waves- electric wave & magnetic wave

• Waves are at 90^o angles

(www.yorku.ca/eye/spectrum.gif)

3 types of spectrums

1. Continuous spectrum

   • unbroken band of color

   • emmits all available wavelengths

   • produced in the center of stars

   (www.astro.washington.edu/stinson/ hlab/images/continuous.gif)

2. Emission spectrum

   • a series of unevenly spaced lines of different colors

   • found in the glowing gas layer of stars

   (www.astro.washington.edu/stinson/ hlab/images/continuous.gif)

3. Absorption spectrum

   • a continuous spectrum with thin areas of dark lines

   • light from a glowing object passes through a cooler gas

   (www.astro.washington.edu/stinson/ hlab/images/continuous.gif)

Electromagnetic wavelengths

Transmission of light

Color of light

Doppler effect