Question

Electromagnetic radiation is more common than you think. Radio and TV stations emit radio waves when they broadcast their programs; microwaves cook your food in a microwave oven; dentists use X rays to check your teeth. Even though they have different names and different applications, these types of radiation are really all the same thing: electromagnetic (EM) waves, that is, energy that travels in the form of oscillating electric and magnetic fields. Which of the following statements correctly describe the various applications listed above? Check all that apply. All these technologies use radio waves, including low-frequency microwaves. All these technologies use radio waves, including high-frequency microwaves. All these technologies use a combination of infrared waves and high-frequency microwaves. Microwave ovens emit in the same frequency band as some wireless Internet devices. The radiation emitted by wireless Internet devices has the shortest wavelength of all the technologies listed above. All these technologies emit waves with a wavelength in the range 0.10 to 10.0 m. All the technologies emit waves with a wavelength in the range 0.01 to 10.0 km. Despite their extensive applications in communication systems, radio waves a not the only form of EM waves present in our atmosphere. Another form of EM radiation plays an even more important role in our life (and the life of our planet): sunlight. The sun emits over a wide range of frequencies; however, the fraction of its radiation that reaches earth's surface is mostly in the visible spectrum. (Note that about 35% of the radiation coming from the sun is absorbed directly by the atmosphere before even reaching the earth's surface.) The earth, then, absorbs this radiation and reemits it as infrared waves. Based on this information, which of the following statements is correct?
1. The earth absorbs visible light and emits radiation with a shorter wavelength.
2. The earth absorbs visible light and emits radiation with a longer wavelength.
3. The earth absorbs visible light and emits radiation with a lower frequency.
4. The earth absorbs visible light and emits radiation with a higher frequency.

Answer 1

Answer:

1) i. All these technologies use radio waves, including high-frequency microwaves.

ii. Microwave ovens emit in the same frequency band as some wireless Internet devices.

2. B. The earth absorbs visible light and emits radiation with a longer wavelength.

Explanation:

Electromagnetic radiations are generated when there is an interference between electric and magnetic fields traveling at right angles to each other. All electromagnetic waves forms a spectrum with respect to their frequency and wavelength. The higher the wavelength, the lower the frequency.

All these waves move with the same and constant speed, but are generated from different sources. From the given applications, X-ray has a high frequency, but low wavelength.

In the second case, infrared waves have longer wavelength than visible light.