1. Electromagnetic spectrum pg. 73

2. Objectives Physics terms
Compare the characteristics and behaviors of electromagnetic waves in various regions of the electromagnetic spectrum.
Investigate and analyze the characteristics of waves in the electromagnetic spectrum that differ in wavelength.
Describe the role of wave characteristics and behaviors in medical and industrial settings.
radiation
gamma rays
x-rays
ultraviolet light
infrared radiation
radio waves
microwaves
electromagnetic spectrum

3. Orders of magnitude
The term “orders of magnitude” refers to powers of ten.
If a quantity spans one order of magnitude, it varies by a factor of ten.
These examples vary by five orders of magnitude: a factor of 105.

4. The electromagnetic spectrum
Point out that we know that all these parts of the spectrum exist even though we cannot see them.

5. The electromagnetic spectrum
The electromagnetic spectrum spans many orders of magnitude in the frequency of electromagnetic waves.
The spectrum ranges from high frequency gamma rays (around 1022 Hz) to low frequency radio waves (around 104 Hz).
Visible light represents only a tiny region of the spectrum.

6. High energy radiation
Gamma rays and x-rays are the highest energy and highest frequency electromagnetic waves. They are used in medical imaging:
Gamma ray PET scans track ingested radioactive substances.

7. High energy radiation
Gamma rays and x-rays are the highest energy and highest frequency electromagnetic waves. They are used in medical imaging:
X-rays are energetic enough to pass through skin but not bones, so they provide skeletal images.

8. Ultraviolet light
Ultraviolet light is more energetic than visible light.
Sunblock protects your skin from possible damage from ultraviolet light.

9. Visible light
Our eyes can detect visible light in a narrow frequency range from about 4 × 1014 Hz to 8 × 1014 Hz.

10. Infrared radiation
Infrared (thermal) radiation has lower energy and lower frequencies than visible light.
Infrared imaging cameras are used to detect thermal leaks in a house, to reduce energy consumption.

11. Microwaves
Microwaves are used in microwave ovens and mobile phone technology.

12. Radio waves
Radio waves are even lower in frequency than infrared light.
They are used for radio and for communication with submarines and man-made satellites.

13. Light waves vs. sound waves
Radio waves are electromagnetic waves—not sound waves.
Electromagnetic waves can travel through many materials and also travel through a vacuum. Sound waves need a medium, such as air.
Electromagnetic waves are transverse waves, while sound waves are longitudinal waves.

14. Homework
Describe one piece of technology that is based on each of the following regions of the electromagnetic spectrum:
x-rays
visible light
infrared light
microwaves
radio waves

15. Homework
2. Identify what type of electromagnetic radiation corresponds to light with each of the following properties.
wavelength of 10 μm
frequency of 1,050 kHz

16. Assessment
Describe one piece of technology that is based on each of the following regions of the electromagnetic spectrum:
x-rays
visible light
infrared light
microwaves
radio waves
medical imaging x-ray machines
digital cameras
thermal imaging cameras
microwave ovens
satellite communication transmitters and receivers
These are only a few of the possible answers!

17. Assessment
Identify what type of electromagnetic radiation corresponds to light with each of the following properties.
wavelength of 10 μm
infrared
frequency of 1,050 kHz
radio waves:
1.05 × 106 Hz