The Electromagnetic Spectrum

Objectives:

    1.    Identify the parts of the electromagnetic spectrum.

    2.    Explain the relationship between wavelength and frequency.

Resources:

 

Notes:

Electromagnetic Spectrum:

        Waves are aligned according to their photon energy, f & l

        Consists of:

        Radio waves

        Infrared

        Visible light

        Ultraviolet

        X-rays

        Gamma rays

Visible spectrum:

        The portion that you can see

        Made up of many different colors (red - violet)

        430 -760 trillion Hz

Invisible Spectrum:

        Frequency above 760 or below 430 trillion Hz

Radio waves - lowest f and highest l

        Used in TV and radio

        l range from 1mm - 30km

        Can be varied by changing amplitude or f

        The changing of f or amplitude is called modulation

AM radio:

        has long l (500,000 - 2mill. Hz)

        Many TV stations - sound

        Long l allows reception around obstacles

FM Stations:

        Modulate frequency

        87mill - 108mill Hz

        Color portion of TV

        Are blocked by large objects

Microwaves:

        1 bill. - 1 trillion Hz

        used for communication or cooking

        Short-l are used in radar

        Radio detecting and ranging

Infrared (IR):

        Just below visible

        Can feel as heat

        Anything that gives off heat gives off IR

Ultraviolet (UV):

        Just above visible

        Photon energy is large enough to kill cells

        Used in hospitals to kill bacteria

        Causes skin to make Vit D - for bones

        Causes skin to burn

X-rays:

        High energy photons can pass through soft tissue

        Absorbed in bone and hard materials such as lead

        Over exposure is harmful

Gamma Rays

        Highest energy photons

        From outer space & certain radioactive materials

        Can penetrate up to 3m in concrete

        Used in medicine to treat cancer

        Exposure con cause severe illness