1. 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?A. All these technologies use radio waves, including low-frequency microwaves. B. All these technologies use radio waves, including high-frequency microwaves. C. All these technologies use a combination of infrared waves and high-frequency microwaves. D. Microwave ovens emit in the same frequency band as some wireless Internet devices. E. The radiation emitted by wireless Internet devices has the shortest wavelength of all the technologies. F. All these technologies emit waves with a wavelength in the range 0.10 to 10.0 m. G. All the technologies emit waves with a wavelength in the range 0.01 to 10.0 km.2. 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? A. The earth absorbs visible light and emits radiation with a shorter wavelength. B. The earth absorbs visible light and emits radiation with a longer wavelength. C. The earth absorbs visible light and emits radiation with a lower frequency. D. The earth absorbs visible light and emits radiation with a higher frequency.

1) The statements that correctly describe the various applications given in the question are;

B. All these technologies use radio waves, including high-frequency microwaves

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

E. The radiation emitted by wireless Internet devices has the shortest wavelength of all the technologies.

F. All these technologies emit waves with a wavelength in the range 0.10 to 10.0 m.

2) The correct statements on the EM spectrum in the question are;

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

C. The earth absorbs visible light and emits radiation with a lower frequency.

1) We are told about different waves being used by different technologies such as;

- Radio and TV emitting radio waves

- microwave oven using microwaves to cook food

- Dentists checking teeth with x-rays

All these waves are electromagnetic waves.

Looking at the options, options B, D, E and F are true because;

2) The correct options are Options B and C because;

In the EM radiation spectrum, when the energy increases, the wavelength usually reduces and the frequency usually increases. The order of  radio waves according to increase in energy is;

radio waves < infrared radiation < visible rays < ultraviolet rays <  xrays < gamma rays.

Now, if we say that the earth absorbs visible rays of higher energy, and radiation of infrared rays with lower energy, then from our definition, we can conclude that radiated waves will have a longer wavelength, and a lower frequency.

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For the first question

Answers:

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

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

e.) The radiation emitted by wireless Internet devices has the shortest wavelength of all the technologies listed above.

f.) All these technologies emit waves with a wavelength in the range of 0.10 to 10.0 m.

For second question

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

C. The earth absorbs visible light and emits radiation with a lower frequency.

Both options are correct

Explanation:

In the EM spectrum, wavelenght reduces with increasing energy and frequency increases with increasing energy. The order of increasing energy is radio wave, microwave, infrared rays, visible rays, ultraviolet rays, xrays, gamma rays.

If the earth absorbs visible rays of higher energy, and radiates infrared rays of lower energy, then this means that the radiated radiation will have a longer wavenght, and a lower frequency.

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