The Electromagnetic Spectrum 1  EM spectrum is complete spectrum of all forms of “light”

 EM wave consists of  electric fields which vibrate  magnetic fields making waves.

2  The EM spectrum consists of:

 radio waves  cell phone waves  microwaves  radar waves  infrared waves  visible light waves  ultraviolet waves  x-ray waves  gamma waves

The Electromagnetic Spectrum 3 The Electromagnetic Spectrum 4  Properties of EM waves include speed, frequency, wavelength

 Speed (c), frequency (f) and wavelength (λ) are related in the formula:

 c = f x λ

 All light waves travel at speed of 3 x 108 m/s in a vacuum

The Electromagnetic Spectrum 5  All parts of EM spectrum travel at same speed.

 λ and f have indirect relationship.

 As one the other

 As λ , f

The Electromagnetic Spectrum 6  As wavelength decreases, frequency does what?  increases

The Electromagnetic Spectrum 7  Electromagnetic wave characteristics: • short wavelengths have a high frequency • long wavelengths have a low frequency

 Electromagnetic waves & Energy: • high frequency waves have high energy • low frequency waves have low energy

The Electromagnetic Spectrum 8 smaller wavelengths have increasing frequency and increasing energy If you haven’t already, sketch this drawing into your notes. Don’t worry so much about the actual wavelengths, just get the general shape and where the various forms of light (radio, infrared, x-ray, etc) exist. The Electromagnetic Spectrum 9 The Electromagnetic Spectrum 10  Low energy waves with longest wavelengths  Includes FM, AM, radar and TV waves  Wavelengths of 1 m (10 -1 m) and longer  Low frequency  Used in many devices such as remote control items, cell phones, wireless devices, etc.

The Electromagnetic Spectrum 11  Only radio waves are longer

 Wavelength 1 x 10-1 m to 1 x 10 - 4 m (1 m to 0.001 m)

 used for communication, medicine and consumer use (microwave ovens)

The Electromagnetic Spectrum 12  Invisible electromagnetic waves that are detected as heat

 Can be detected with special devices such as night goggles

 Used in heat lamps

 Higher energy than microwaves but lower than visible light

The Electromagnetic Spectrum 13  The portion of the EM spectrum that human eyes can detect.

 ROY G BIV (red, orange, yellow, green, blue, indigo, violet)

 Which color has the lowest frequency?  red has the lowest frequency – violet the highest

The Electromagnetic Spectrum 14 The Electromagnetic Spectrum 15  Higher energy than light waves

 Can cause skin cancer and blindness in humans

 Used in tanning beds and sterilizing equipment

The Electromagnetic Spectrum 16  High energy waves

 Used in medicine, industry and astronomy

 Can cause cancer

The Electromagnetic Spectrum 17 Highest energy

Blocked from Earth’s surface by atmosphere

The Electromagnetic Spectrum 18 The Electromagnetic Spectrum 19 1. What is the relationship between frequency and wavelength?

2. What characteristic of gamma waves gives them their high energy?

3. What does ROY G BIV mean? What part of the electromagnetic spectrum does it refer to?

The Electromagnetic Spectrum 20 4. Which color is more energetic, red or yellow?

5. Which type of wave travels faster, gamma or radio?

6. Why are microwaves more dangerous than radio waves?

The Electromagnetic Spectrum 21 7. You have just been involved in a traffic incident that leaves you stranded on the side of the road. Which part of the electromagnetic spectrum would be of the most use to you and why?

The Electromagnetic Spectrum 22 1. Frequency and wavelength are properties of waves and since speed is constant for em waves, as frequency increases, wavelength decreases. In other words, they have an indirect relationship.

2. Gamma waves get their high energy from their extremely short wavelengths (or extremely fast frequency)

3. ROY G BIV stands for “red, orange, yellow, green, blue, indigo, and violet. They are the colors of the visible light in order of longest wavelength to shortest wavelength.

4. Yellow is more energetic than red because it has a shorter wavelength (or larger frequency)

5. Gamma waves and radio waves travel at the same speed

6. Microwaves are more dangerous than radio waves because they have a higher frequency and carry more energy.

The Electromagnetic Spectrum 23