Добавил:
Upload Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз: Предмет: Файл:
Английский 2 метода.doc
Скачиваний:
62
Добавлен:
29.05.2015
Размер:
219.14 Кб
Скачать

Electrical Circuit Ideas

By James Stevens, eHow Contributor

Ring Circuits

A ring circuit is the most common type of circuit, linking all the wall sockets in a home. Most homes have one main ring circuit for each floor. A ring circuit is usually a high ampere circuit so that it can adequately provide electricity to many high-energy electrical items at the same time. The ring circuit starts at the fuse box, runs to each electrical outlet, then returns to the fuse box. The advantage of a ring circuit is that power flows from two directions and this reduces the overall load through the wiring.

Radial Circuits

Radial circuits serve fewer outlets and often connect directly to one or two specific items, such as a stove or central electric heating system. These types of items need a separate dedicated circuit due to their power consumption. A radial circuit starts at the fuse box and ends at the last device it's wired to. Unlike a ring circuit, it doesn't return to the fuse box.

Lighting Circuit

Lighting circuits are generally similar to radial circuits, except the wiring used is thinner as the ampere requirement is less. The wiring starts at the fuse box, runs to each light socket, and ends at the last light socket. An individual wire is connected between each light socket and the corresponding light switch in a loop system. If your home has two levels, you will usually have two separate lighting circuits.

Converting Circuits

If you need to install more sockets in your home, one idea is to convert a radial circuit into a ring circuit. This means you don't have to install completely new wire, you can just extend the existing wiring. The wiring to the last socket in the radial circuit continues to as many new sockets as you need. When you've fitted the last socket, the wire returns to the fuse box making a ring circuit. Converting a radial circuit to a ring circuit should be done by an electrician.

Text 5

Practice 1. Choose the key sentence in each paragraph.

Practice 2. Re-read the text to find out the author’s main idea:

1. This research will completely change the theory of magnetism.

2. The findings could lead to a reassessment of current magnetism theories, as well as significant technological advances.

3. The experiment allowed the team to detect magnetic charges in the spin ice, to measure their currents, and to determine the elementary unit of the magnetic charge in the material

4. A magnetic charge can behave and interact just like an electric charge in some materials.

Practice 3.Make a review of the text.

'Magnetricity' Observed And Measured For First Time

ScienceDaily (Oct. 15, 2009)

The research, published in Nature, proves the existence of atom-sized ‘magnetic charges’ that behave and interact just like more familiar electric charges. It also demonstrates a perfect symmetry between electricity and magnetism – a phenomenon dubbed ‘magnetricity’ by the authors from the LCN and the Science and Technology Facility Council’s ISIS Neutron and Muon Source.

In order to prove experimentally the existence of magnetic current for the first time, the team mapped Onsager’s 1934 theory of the movement of ions in water onto magnetic currents in a material called spin ice. They then tested the theory by applying a magnetic field to a spin ice sample at a very low temperature and observing the process using muons at ISIS.

The experiment allowed the team to detect magnetic charges in the spin ice (Dy2Ti2O7), to measure their currents, and to determine the elementary unit of the magnetic charge in the material. The monopoles they observed arise as disturbances of the magnetic state of the spin ice, and can exist only inside the material.

Professor Steve Bramwell, LCN co-author of the paper, said: “Magnetic monopoles were first predicted to exist in 1931, but despite many searches, they have never yet been observed as freely roaming elementary particles. These monopoles do at least exist within the spin ice sample, but not outside.

“It is not often in the field of physics you get the chance to ask ‘How do you measure something?’ and then go on to prove a theory unequivocally. This is a very important step to establish that magnetic charge can flow like electric charge. It is in the early stages, but who knows what the applications of magnetricity could be in 100 years time.”

Professor Keith Mason, Chief Executive of STFC said: “The unequivocal proof that magnetic charge is conducted in spin ice adds significantly to our understanding of electromagnetism. Whilst we will have to wait to see what applications magnetricity will find in technology, this research shows that curiosity driven research will always have the potential to make an impact on the way we live and work. Advanced materials research depends greatly on having access to central research labs like ISIS allowing the UK science community to flourish and make exciting discoveries like this.”

Dr Sean Giblin, instrument scientist at ISIS and co-author of the paper, added: “The results were astounding, using muons at ISIS we are finally able to confirm that magnetic charge really is conducted through certain materials at certain temperatures – just like the way ions conduct electricity in water.”

Text 6

Practice 1. Choose the key sentence in each paragraph.

Practice 2. Re-read the text to find out the author’s main idea:

1. At the moment, the researchers are working to develop a good method to capture the nanowires and make them self-assemble in an ordered manner on a specific surface.

2. A completely new method of manufacturing the smallest structures in electronics could make their manufacture thousands of times quicker, allowing for cheaper semiconductors

3. Instead of starting from a silicon wafer or other substrate, as is usual today, researchers have made it possible for the structures to grow from freely suspended nanoparticles of gold in a flowing gas

4. Reasearchers have built a prototype machine with a specially built oven.

Practice 3. Make a review of the text.