GENERATORS

       The powerful, highly efficient generators and alternators that are in use today operate on the same principle as the dynamo invented by the great English scientist Faraday in 1831.

       Dynamo-electric machines are used to supply light, heat and power on a large scale. These are the machines that produce more than 99.99 per cent of all the world's electric power.

      There are two types of dynamos – the generator and the alternator. The former supplies d. c. which is similar to the current from a battery and the latter provides a. c. To generate electricity both of them must be continuously provided with energy from some outside source of mechanical energy such as steam engines, steam turbines or water turbines.

      A generator is an electric machine, which converts mechanical energy into electric energy. There are direct-current (d. c.) generators and alternating-current (a. c.) generators. Their construction is much alike. A d. c. generator consists of stationary and rotating elements. The stationary elements are: the yoke or the frame and the field structure. The yoke forms the closed circuit for the magnetic flux. The function of the magnetic structure is to produce the magnetic field.

         What is an electricity generator? 

    An electricity generator is a device for converting mechanical energy into electrical energy. The process is based on the relationship between magnetism and electricity. When a wire or any other electrically conductive material moves across a magnetic field, an electric current occurs in the wire. The large generators used by the electric utility industry have a stationary conductor. When the magnet rotates inside the stationary conductor it induces a small electric current in each section of wire as it passes. Each section of wire constitutes a small, separate elastic conductor. All the small currents of individual sections add up to one current of considerable size. This current is what is used for electric power.

ELECTRIC CIRCUITS 

The concepts of electric charge and potential are very important in the study of electric currents. When an extended conductor has different potentials at its ends, the free electrons of the conductor itself are caused to drift from one end to the other. The potential difference must be maintained by some electric source such as electrostatic generator or a battery or a direct current generator. The wire and the electric source together form an electric circuit, the electrons are drifting around it as long as the conducting path is maintained.

ELECTRIC CURRENT

The electric current is a quantity of electrons flowing in a circuit per second of time. The unit of measure for current is ampere. If one coulomb passes a point in a circuit per second then the current strength is 1 ampere. The symbol for current is I. 

The current which flows along wires consists of moving electrons. The electrons move along the circuit because the e.m.f. (electromotive force) drives them. The current is directly proportional to the e.m.f. 

In addition to traveling through solids, however, the electric current can flow through liquids as well and even through gases. In both cases it produces some most important effects to meet industrial requirements.

WHAT IS ELECTRICITY? 

Electricity is a form of energy. Electricity is a flow of electrons. All matter is made of atoms, and an atom has a center, called a nucleus. The nucleus contains positive charges called protons and uncharged called neutrons. The nucleus of atom is surrounded by negatively charged particles called electrons. The negative charge of electron is equal to the positive charge of a proton, and the number of electrons in an atom is usually equal to the number of protons. When the balancing force between protons and electrons is upset by an outside force, an atom may gain or lose an electron. When electrons are “lost” from an atom, the free movement of these electrons constitutes an electric current. 

Electricity is a basic part of nature and it is one of our most widely used forms of energy. We get electricity, which is a secondary energy source, from the conversion of other sources of energy, like coal, natural gas, oil, nuclear power and other natural sources, which are called primary energy.

The Structure of the Application letter. 

Plan. Examples.

Plan	What to write	Examples
FORMAL GREETING		Dear Sir/Madam, Dear Mr./Mrs. Smith,
INTRODUCTORY PARAGRAPH / OPENING REMARCS	·  reason for writing – you say why you are writing and ·  where post was advertised	I would like to apply for … I am writing to apply for … I am writing to apply for the position of… I am writing in response to your advertisement which appeared in the .... on …. . With reference to your advertisement… I am writing to apply for… I am very interested in getting the position of…
MAIN BODY (you have to persuade the reader that you are the best person for the job!)	·  what you are doing now	At the moment I am a student at… I am in my last year of ….
	·   qualifications ·  experience ·  responsibilities ·  skills	I have experience of working in… My previous responsibilities/duties included …  I am good at… / I have a good knowledge of….. I am a fast learner. I have excellent communication skills. I have a good command of English.
	·  personal characteristics / what you are like	I would describe myself as punctual/hard-working/ decisive/ sociable…
	·  suitability	I consider myself to be suitable…
CONCLUSION	·  when available for the interview	I am available for the interview on.. I am available for the interview at any time. I am available for the interview any day till 4 p.m.
	·  contact details	I can be contacted by phone …. / e-mail
	·  enclosures	I would be grateful if you could look at my CV / references from the previous employer I enclosed to this letter. I have enclosed a copy of my CV.
CLOSING REMARCS		I would be grateful if you would consider my application. I look forward to hearing from you soon.
FORMAL ENDING		Yours faithfully, (you don’t know the name) Yours sincerely, (you know the name)
SIGNATURE	·  your full name

BUSINESS LETTERS 

NOTES ON LETTER WRITING