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Chapter 4: Problem 3

If you and a friend are on opposite sides of a hill, you can communicate with walkie-talkies but not with flashlights. Explain.

Short Answer

Expert verified
In conclusion, walkie-talkies use radio waves, which have a lower frequency and longer wavelength than light waves, allowing them to diffract around obstacles like a hill and maintain communication. On the other hand, flashlights use light waves, which require a direct line of sight and cannot diffract around the hill, making communication impossible in this situation.

Step by step solution

01

Understanding the Properties of Radio Waves and Light Waves

Both walkie-talkies and flashlights use electromagnetic waves as a medium to transfer information. However, walkie-talkies use radio waves, which are a lower frequency and longer wavelength compared to light waves. Due to their lower frequency, radio waves can diffract (spread out) more easily around obstacles such as a hill. On the other hand, light waves have a higher frequency and shorter wavelength, making them less likely to diffract around obstacles.
02

Radio Waves and Diffraction

When radio waves encounter an obstacle, such as a hill, they can diffract around it and continue to travel beyond the obstacle. This ability to diffract enables radio waves to maintain communication between two points even when there is a solid object in between them, like a hill. So, when you and your friend use walkie-talkies, the radio waves are able to travel around the hill and reach your friend on the other side.
03

Light Waves and Line of Sight

Conversely, light waves are less capable of diffracting around obstacles. When a light wave encounters an obstacle, it will either be absorbed or reflected by the material, making it unable to travel beyond the obstacle. This characteristic means that for a flashlight to be effective in transmitting or receiving a signal, there must be a direct line of sight between the two points. So, when you and your friend are on opposite sides of a hill, the light from a flashlight cannot reach your friend due to the absence of a direct line of sight.
04

Conclusion

In conclusion, when you and your friend are on opposite sides of a hill, you can communicate with walkie-talkies but not with flashlights because walkie-talkies use radio waves, which are capable of diffracting around the hill, whereas flashlights use light waves, which require a direct line of sight.

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