# PH.9 - Frequency and Wavelength

The student will investigate and understand that different frequencies and wavelengths in the electromagnetic spectrum are phenomena ranging from radio waves through visible light to gamma radiation. Key concepts include

a)  the properties, behaviors, and relative size of radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays;

b)  wave/particle dual nature of light; and

c)  current applications based on the respective wavelengths.

Bloom's Levels:  Analyze; Understand

### BIG IDEAS

• I can explain why a fire truck's siren seems to change sound as it passes by.
• I can explain how light acts as both a wave and particle.
• I can explain how satellite radio works.

### UNDERSTANDING THE STANDARD

The concepts developed in this standard include the following:

• Frequency, wavelength, and energy vary across the entire electromagnetic spectrum.
• The long wavelength, low frequency portion of the electromagnetic spectrum is used for communication (e.g., radio, TV, cellular phone).
• Medium wavelengths (infrared) are used for heating and remote control devices.
• Visible light comprises a relatively narrow portion of the electromagnetic spectrum.
• Ultraviolet (UV) wavelengths (shorter than the visible spectrum) are ionizing radiation and can cause damage to humans. UV is responsible for sunburn, and can be used for sterilization and fluorescence.
• X-rays and gamma rays are the highest frequency (shortest wavelength) and are used primarily for medical purposes. These wavelengths are also ionizing radiation and can cause damage to humans.

### ESSENTIALS

In order to meet this standard, it is expected that students will

a)  describe the change in observed frequency of waves due to the motion of a source or a receiver (the Doppler effect).

c)  identify common uses for radio waves, microwaves, X-rays and gamma rays.

### KEY VOCABULARY

Updated: Dec 01, 2017