There are some benefits to any common ground for all of the provided options, but the key here is that it is specifically an "external earth connection or ground rod" -- in other words, this ground is actually going into the ground outside, not just into a common terminal which has been dubbed "ground" or into the house "ground".

The main reason to do that is that in the case of a lightning strike the current will take the path of least resistance to get to earth ground and you want that path to be both as short as possible and to get there much more easily than it can get to your equipment.

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NOTE: Many people have contacted the HamStudy team to report this question as having duplicate answers, but each answer is unique!. The key words to watch for are exposure vs emission and controlled vs uncontrolled.

The correct answer is uncontrolled and exposure. Don't be fooled by answers with Emission in them. Exposure is the word used in this question.

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The two sets of exposure limits are controlled and uncontrolled. If you don't have the ability to restrict access to the area of exposure, then you must use the uncontrolled exposure limits.

In this case, you can't control where your neighbor is nor prevent him/her from being in an area of exposure, hence, you must use the uncontrolled MPE (Maximum Permissible Exposure) limits.

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FCC human body RF exposure limits are most restrictive for those frequencies where the human body may present a resonant wavelength. This is where the maximum absorption might occur.

The average height of a human male is 5' 9" or 1.75 meters. For females this is 5' 4" or 1.6 meters. This corresponds to a full wavelength of 171 to 188 MHz and a half wavelength of 85 to 94 MHz. These frequencies fall in the VHF range of 30-300MHz.

Silly Hint: 0uch to 0uch 0uch. The answer with one zero to 2 zeros.

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This is an FCC rule designed to avoid arguments. In essence, any station that provides a significant portion of the transmitted power is responsible to ensure exposure limits are met.

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In the microwave range, the wavelengths are fairly small. This allows easy, inexpensive construction of high-gain antennas. The small size of the antenna can be deceptive relative to the high field strength it can generate. Caution must be used to protect people when using these antennas.

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All of these are correct and should be accounted for when considering Maximum Permissible Exposure (MPE) limits.

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Carbon monoxide is a colorless, odorless, and tasteless gas. It's a little lighter than air and will rise filling a space from the top down. The only way to detect the gas is with a carbon monoxide detector. The gas is also called carbonous oxide and has one atom of carbon and one atom of oxygen.

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SAR, in this case, stands for Specific Absorption Rate. This is the rate at which the human body absorbs energy from an electromagnetic field. The SAR is affected by both frequency and body part.

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Beryllium Oxide (BeO) is listed as a serious respiratory irritant and probable carcinogenic. Why is it used? Because while most electrical insulators are poor thermal conductors, BeO is good at both. Because it is both a good electrical insulator and a good thermal conductor, it is used in semiconductors and in some vacuum tubes. If either of these types of devices are damaged, be aware of any white dust, as it may be BeO, which is a white ceramic material. Avoid skin contact or inhalation. You can also determine if BeO is used by consulting the manufacturers data sheet. Further information is available on the MSDS (Material Safety Data Sheet) for BeO, several of which may be found using an internet search.

Test Hint: BO can be very toxic

Silly Hint: Nobody wants to inhale BO (smell body odor).

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You may recognize these as PCB's because they were commonly used and attracted a considerable amount of bad press. PCB's had the advantage of improving the stability and insulating qualities of transformer oil. Unfortunately, they were also shown to be carcinogenic and were subsequently removed from future use. This is mostly a problem in older, large transformers and capacitors.

Exam hint: PCB (Polychlorinated biphenyls) and PCB (Printed circuit board) are both present in electronics.

Cheat: Bi phenyls may be present.

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Basically a high power UHF or microwave transmitter is doing the same thing as what a microwave oven would do; the frequency may be different, but higher UHF and microwave RF radiation can cause localized heating, just like a microwave would if you ran it with the door open and stuck your arm in.

The specific area that would be heated and the severity of the damage would depend on the frequency and the radiation pattern of the antenna, but you should always be cautious whenever using a high power UHF or microwave signal.

Hint: think about microwave oven which also works in UHF band.

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