About Electromagnetic Pulse

Electromagnetic Pulse (EMP) is an instantaneous, intense energy field that can overload or disrupt at a

distance numerous electrical systems and high technology microcircuits, which are especially sensitive to power surges.  A large scale EMP effect can be produced by a single nuclear explosion detonated high in the atmosphere.  This method is referred to as High-Altitude EMP (HEMP).  A similar,smaller-scale EMP effect can be created using non-nuclear devices with powerful batteries or reactive chemicals.  This method is called High Power Microwave (HPM).  Several nations, including reported sponsors of terrorism, may currently have a capability to use EMP as a weapon for cyber warfare or cyber terrorism to disrupt communications and other parts of the U.S. critical infrastructure.  Also, some equipment and weapons used by the U.S. military may be vulnerable to the effects of EMP.

 The threat of an EMP attack against the United States is hard to assess, but some observers indicate that it is growing along with worldwide access to newer technologies and the proliferation of nuclear weapons.  In the past, the threat of mutually assured destruction provided a lasting deterrent against the exchange of multiple high-yield nuclear warheads.  However, now even a single, low-yield nuclear explosion high above the United States, or over a battlefield, can produce a large-scale EMP effect that could result in a widespread loss of electronics, but no direct fatalities, and may not necessarily evoke a large nuclear retaliatory strike by the U.S. military. This, coupled with published articles discussing the vulnerability of U.S. critical infrastructure control systems, and some U.S. military battlefield systems to the effects of EMP, may create a new incentive for other countries to rapidly develop or acquire a nuclear capability. Policy issues raised by this threat include (1) what is the United States doing to protect civilian critical infrastructure systems against the threat of EMP, (2) could the U.S. military be affected if an EMP attack is directed against the U.S. civilian infrastructure, (3) are other nations now encouraged by U.S. vulnerabilities to develop or acquire nuclear weapons, and (4) how likely are terrorist organizations to launch a smaller-scale EMP attack against the United States ?

There is more to the story than a list of questions. A way more interesting to learn EMP is online tutoring. with online math tutoring you’ll get math answers by submitting your math problems. some Precalculus help that we got from online tutoring is very useful. EMP has a lot of precalculations and we are sure about it. you can also get something like statistics help or even chemistry help. this is a fun and good way to learn EMP mathematics.

Electromagnetic Wave

Radio wave is electromagnetic wave. We know longitudinal wave and transversal wave also. The wave concept is from basic math for physical phenomena. It explains how the wave moves, interact, and get deflected. All waves are f = f (xąvt),it’s a math, and when you need math help,you can find online math tutor that will help you a lot about this in the internet. Wave is not an easy part of math and physic,but with online math tutoring, you’ll get the answer quickly.

Actually to learn radio wave with online math help is one of the way to get the science. You can try books, but you still need direct tutorial. You can find free online math tutoring to get the basic understanding for radio wave.then you can explore the knowledge by yourself. Internet helps you a lot for this kind of problem, and free online math help is a nice move to start. Online math help is helping you not only with the radio wave and math,but also interact with people and that is important, considering some of scientist are never actually meet real people but numbers.

Back to topic, radiowave is somehow around us and we can take advantages by using it wisely. For the sake of science,that all we have and we know are for the human prosperity and the everlasting world for our next generations.

Basic Differences Between AM and FM

We need to mention a couple of other things before we leave the discussion of how radio works.  We’ve talked about AM and FM radio, but we haven’t explained the real difference.

In fact, there is a lot of difference — and not just a difference in the station numbers on your radio dial.

The first type of radio service — the one we’ve been talking about in the last couple of modules — was AM radio.

The term modulation refers to how sound is encoded on a radio wave called a carrier wave; or, more accurately, how the sound affects the carrier wave so that the original sound can later be detected by a radio receiver.

In the top-left of this drawing the RF energy (carrier wave) is not modulated by any sound.  There would be silence on your radio receiver.

Sound transmitted by an AM radio station affects the carrier wave by changing the amplitude (height) of the carrier wave, as shown on the left.

Unfortunately, this type of modulation is subject to static interference from such things as household appliances — and especially from lightening storms.

AM also limits the loud-to-soft range of sounds that can be reproduced (called dynamic range) and the high-to-low sound frequency range (called frequency response, to be explained below).

FM radio, which came along in the 1930s, uses a different approach than AM. It’s virtually immune to any type of external interference, it has a greater dynamic range, and it can handle sounds of higher and lower frequencies. This is why music, with its much greater frequency range than the human voice, sounds better on FM radio.

Note on the left that when the carrier wave of FM radio is modulated with sound that the distance between the waves, or the frequency of the carrier wave, changes.

Thus, AM radio works by changing the amplitude of the carrier wave and FM radio works by changing the frequency of the carrier wave.

Frequency Response

Frequency relates to the basic pitch of a sound — how high or low it is. A frequency of 20 Hz would sound like an extremely low-pitched note on a pipe organ — almost a rumble.

At the other end of the scale, 20,000 Hz would be the highest pitched sound that can be imagined, even higher than the highest note on a violin or piccolo.

As we’ve noted, frequency is measured in Hertz (Hz) or cycles per second (CPS). A person with exceptionally good hearing will be able to hear sounds from 20-20,000 Hz.

Since both ends of the 20-20,000Hz range represent rather extreme limits, the more common range used for FM radio and TV is from 50 to 15,000 Hz. (A typical AM radio signal does not cover this entire range.)

Although the 50-15,000 Hz doesn’t quite cover the full range that can be heard by people with good hearing, it covers almost all naturally occurring sounds.  Note in the drawing above that the ear does not hear all frequencies of sound at the same loudness, but a good microphone does.

The sound level or amplitude of sound in radio and TV stations is monitored and adjusted with the help of a volume units meter (VU meter) meter. One model is shown on the left.  Audio levels must be carefully controlled in broadcasting to keep noise and distortion from reducing the quality of sound.