.... the electric current is made of atoms which have equal numbers of protons and electrons making the atoms electrically neutral. If this balance is disturbed by gain or loss of electrons, the atoms will become electrically charged and are called ions. Electrons occupy energy states. Each level requires a certain amount of energy. For an electron to move to a higher level, it will require the right amount of energy. Electrons can move between different levels and between different materials but to do that, they require the right amount of energy and an "empty" slot in the band they enter. The metallic conductors have a lot of these slots and this is where the free electrons wil ....

.... 90 per cent of the acid rain that falls over Norway originates in other countries. · Cuts in emissions have reduced the acidity of rain and snow recently. Total emissions of sulphur in Europe were reduced by more than 40 per cent from 1980 to 1993. In the same period, Norway's emissions were reduced by more than 70 per cent. · As a result of higher precipitation in recent years, sulphur deposition has not dropped as much as might be expected from the reductions in emissions. · Estimates of how much pollution the environment can absorb without damage are called critical loads. · Sulphur, like nitrogen, is essential to all animals and plants. The natural sulphu ....

.... going back to AD 1400. The study places in a new context long-standing controversy over the relative roles of human and natural changes in the climate of past centuries, according to Mann. Scientists were particularly interested in natural "forcings" -- factors that can affect the climate significantly but which are not part of the climate system itself. Based on statistical comparisons of reconstructed northern hemisphere temperatures, the best estimates indicate that natural changes in the brightness of the sun and volcanic emissions both played an important role in governing climate variations over the period studied. But over the past few decades, greenhouse gases produc ....

.... areas of the beach as news media arrived to cover the Exxon people’s taping.14 As bad as the Valdez disaster was, Exxon made five billion dollars of revenue during the 1989 operating year. Of that, they spent three billion over the next several years on the clean up. During the cleanup, Exxon employed the assistance of 12,000 people and 1,385 ships and planes. They recovered a little over 2.6 million gallons of oil from Prince William Sound over the cleanup period. The estimated number of dead birds was 33,126 along with 138 eagles and 980 otters. Usually, when we are thinking of oil pollution what comes to mind is maybe a disastrous oil tanker spill somewhere in an ....

.... the pests that impact on agriculture. They are the best ways to boost agricultural output and still save the environment. The U.S. could have been using biotechnology as early as the late 1800's. USDA entomologist C.V. Riley was quoted in an article written by Sean Adams for Agricultural Research. Adams uses Riley’s quote from 1882 saying that the evidence for the use of natural enemies and parasites to control pests is sufficient to support their use. (16). Even so, pesticides have been used for centuries. In James Whorton’s book, Before Silent Spring, he describes agriculture before the Industrial Revolution. He writes that farmers in the 1800's used arsenic ....

.... varies in the frequency or shape of the light wave. Because light waves are of much higher frequencies than radio waves, the have a higher information carrying capacity. In beams of light,individual photon waves are not moving along together because they are not being emitted at the same instant but instead in random short bursts. Such beams are called incoherent. The process for laser action, was first proposed by Albert Einstein in 1917. The working principles of lasers were outlined by the American physicists Arthur Leonard Schawlow and Charles Hard Townes in their 1958 patent application. The patent was granted but was later challenged by the American physicist a ....

.... worst type of MS. According to the National Society a person with primary-progressive MS is “characterized by a gradual but steady progression of disability from the onset, with no obvious plateaus or remissions, or only occasional plateaus and minor, temporary improvements.” In short this means that the symptoms Kathy is experiencing such as falling down due to a lack of coordination, tiredness, numbness, and bladder problems are only going to get worse. But possibly the worst symptom of all are mental problems such as a loss of self-esteem and feelings of worthlessness. The most obvious effect that MS has on a person is a loss of coordination and balance ....

.... and residential fuel combustion together contribute most of the rest. In the air, the sulphur dioxide and nitrogen oxides can be transformed into sulphuric acid and nitric acid, and air current can send them thousands of kilometres from the source.When the acids fall to the earth in any form it will have large impact on the growth or the preservation of certain wildlife. NO DEFENCE Areas in Ontario mainly southern regions that are near the Great Lakes, such substances as limestone or other known antacids can neutralize acids entering the body of water thereby protecting it. However, large areas of Ontario that are near the Pre©Cambrian Shield, wi ....