3.5.1.1 Introduction
Since 1950's the electromagnetic geophysical methods have been used extensively and with great success to delineate conductive zones at depths. The aim of EM method responds to high conductivities rather than to contrasts in conductivity as is the case with the classical direct current (DC) method. This means that EM methods can detect small changes in conductivity in a conductive terrain by the correct selection of technique and array and secondly that resistive layers became transparent in contrast to the DC resistivity method where penetration of such layers is difficult. According to (Mares et al., 1984) the EM methods can be divided into three fundamental groups:
1. Location of local conductors in a non-conducting or conducting medium. This is the main problem of EM ore mineral prospecting, because ore bodies frequently form good conductors. EM methods are similarly used in investigating conductive tectonics, man-made conductors.
2. Detect rocks of different conductivities. In such case the EM methods make use of the dependence of one of the measured quantities
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The latter is then divided into bands of extremely low frequencies (ELF) up to 1.0 kHz and very low frequency over 1.0 kHz. The notation very low frequencies has been adopted from Radio engineering; frequencies from hundreds thousands of Hz are usually pointed to low. The variable electromagnetic field in the microplusation range has its sources mostly in discharges in the ionosphere and is referred to as the magneto-telluric field of the earth. The methods which make use of the dependence of the distribution of the magneto-telluric field on the conductivity in the earth's crust are called magneto-telluric methods. Using ultra- low frequencies these methods can have a large depth range, even of over 100
In MOD’s excel workbook I have used many macros to create shortcuts to different sheets and also macros to perform various tasks. Overall using macros will speed up how fast the end user can use and navigate the sheet and also make it easier to use. I have also used auto-sum, this automatically entered in a certain formula that I had chosen. By using auto-sum I saved time by not having to enter in long formulas. I have also used an automated filter tool, this tool filters out any data that the user decides is unneeded, which will help the user as it does not show data that useless to them or is unneeded.
For example, gold mines could be found in places like Macedonia while copper mines could found on the islands of Delos or Eretria. Also, it is important to note that bronze is a mix of tin and copper so it can not be mined directly from the earth. These metals were primarily used for the production of arms and currency during this time period. These metals were often found through underground mining, also known as deep vein mining. This type of mining was tedious and could only be done through excavation and tunnel building. These tunnels eventually emptied into galleries where ore was obtained, washed and melted. There was often a “relay of miners carrying ore out on their shoulders” while other times wheeled carts were used. Another type of mining was surface mining where ore surfaced in streams or on the ground and collected. An example of surface mining is placer deposits where streams broke up the ore and the dense pieces would settle at the bottom. The Greeks were very intelligent and could tell the “affinity for one type of metal for another” or would follow the placer deposits to the source. Because of the presence of water previously, sometimes the mine was forced to be abandoned because of the lack of control of the water. The Romans attempted to counteract this by digging drainage adits to divert water and filtering the water by percolation. Slaves would often carry the water away with
Riley, C.M. "Lahars." Geological and Mining Engineering Sciences. Michigan Tech. Web. 6 Feb. 2010. .
could be used to explain and illustrate that previous theories were not entirely correct (Merali and Skinner, 2009, p.253). Through the analyzation of arrival times of these waves, Oldham had drawn an conclusion that p waves and s waves react differently in terms of being refracted, reflected or absorbed depending on the state of the material as shown in Figure 1.(Tarbuck, Lutgens, Tasa, 2013, p.143). Oldham had developed this theory of the Earth not being the same state due to these effects of seismic discontinuity which are shown in Figure 1., consisting of refraction, reflection and absorption. The changes that are displayed from this idea are; the speed of the waves due to a refraction occu...
EMTALA stands for the Emergency Medical Treatment and Active Labor Act. Congress passed the legislation in 1986, making it a federal law. EMTALA states that anyone showing up into the Emergency Department of a Medicare payment receiving hospital, seeking medical attention, must be seen regardless of the individual’s ability to pay. Although, the law is directed towards Medicare accepting hospitals it addresses any and all people wanting medical attention. Relatively all hospitals in the United States participate in and receive monies from Medicare. That is relatively all hospitals in the U.S. are governed by the EMTALA legislation. The wording of “anyone” coming into an Emergency Department is EMTALA’s attempt to cover every person in the U.S. experiencing a medical crisis.
Michael Faraday was the man behind the discovery of electromagnetic induction. Electromagnetic induction is the creation of an electric current by using a magnetic field. Faraday’s first experiment was set up by coiling to separate lengths of copper wire around a wooden block. The two coils had to be separated he did this with thread. One of the coils was connected to a galvanometer (an instrument used to detect small electrical currents), while the second coil was connected to a battery and switch. As Faraday closed the switch there was a small and brief change in the reading on the galvanometer. What this meant was that Faraday had seen a little and concise current that passed through the galvanometer circuit. Faraday observed the same affect in the galvanometer circuit when the battery circuit was turned off, except the change was in the opposite direction or negative of the first reading of the galvanometer.
Answer: The advantages of using several gap to measure the transfer or contact resistance using the TLM (transmission line method) are as follows:
making observations on rock samples from the earth and recording data. If the area seems
Emergency care has always been an important part of history all over the world. It has been said that medical assistance has been around and prevalent since as far back as 1500 B.C. Around the 1700’s is when EMS systems first began to experience large advancements, and ever since then, the field continues to grow and improve every year.
Electricity is an interesting subject. There is so much you can learn from it, like how our lights turn on or how we make cell phones. This is all a mystery until we finally get a little bit of information in our brains. I've just read two articles, "Energy Story" and "Conducting solutions". I also watched a video called Hands-on Science with Squishy circuits. I learned so much valuable information from these resources.
Knowledge of the internal structure section of the earth's crust and the outer part of the Earth's atmosphere; because the lava issued from this level, a depth of about 450 kilometers.
This experiment was conducted to determine how the electrical conductivity of an aqueous solution of Sodium Chloride (NaCl) would be affected by the amount of dissolved NaCl in solution (concentration).
How to test for this: a Metal plate is attached to a galvanometer with two wires, if a light with the right frequency and wavelength is shone upon it, a current will be registered with the galvanometer. (A Galvanometer measures the electric current and the flow of it.) The readings might show that electrons have been ejected. The ejected electrons flow through wires to the galvanometer and that causes a reading.
Scientists and engineers have been able to enhance our lifestyles by understanding and using the Laws, Concepts and Principles of Optics and how they are applied in Optical Instruments. The key concepts are:
waves are further divided into two groups or bands such as very low frequency (