Table of Contents
BEST IELTS General Reading Test 235
IELTS GENERAL READING TEST – 235 PASSAGE – 2
IELTS GENERAL READING TEST
READING PASSAGE – 2
History of Wells
A well is an excavation or structure created in the ground by digging, driving, or drilling to access liquid resources, usually water. The oldest and most common kind of well is a water well to access groundwater in underground aquifers. The well water is drawn up by a pump, or using containers, such as buckets, that are raised mechanically or by hand. Water can also be injected back into the aquifer through the well. Wells were first constructed at least eight thousand years ago and historically vary in construction from a simple scoop in the sediment of a dry watercourse to the qanats of Iran, and the stepwells and sakiehs of India. Placing a lining in the well shaft helps create stability, and linings of wood or wickerwork date back at least as far as the Iron Age.
IELTS General Reading Test
Wells have traditionally been sunk by hand digging, as is the case in rural areas of the developing world. These wells are reasonable and low-tech as they use mostly manual labour, and the structure can be lined with brick or stone as the excavation proceeds. A more modern method called crimsoning uses pre-cast reinforced concrete well rings that are lowered into the hole Driven wells can be created in unconsolidated material with a well hole structure, which consists of a hardened drive point and a screen of perforated pipe, after which a pump is installed to collect the water. Deeper wells can be excavated by hand drilling methods or machine drilling, using a bit in a borehole. Drilled wells are usually cased with a factory-made pipe composed of steel or plastic. Drilled wells can access water at much greater depths than dug wells.
IELTS General Reading Test
Two broad classes of well are shallow or unconfined wells completed within the uppermost saturated aquifer at that location, and deep or confined wells, sunk through an impermeable stratum into an aquifer beneath. A collector well can be constructed adjacent to a freshwater lake or stream with water percolating through the intervening material. The site of a well can be selected by a hydro geologist, or groundwater surveyor. Water may be pumped, or hand drawn. Impurities from the surface can easily reach shallow sources and contamination of the supply by pathogens or chemical contaminants needs to be avoided.
Well water typically contains additional minerals than surface water and may require treatment before being potable. Soil salination can occur as the water table falls and the surrounding soil begins to dry out. Another environmental problem is the potential for methane to seep into the water. Wood-lined wells are known from the early Neolithic Linear Pottery culture, for example in Ostrov, Czech Republic, dated 5265 BC, Kückhoven (an outlying centre of Erkelenz), dated 5090 BC, and Eythra in Schletz (an Zoutlying centre of Aspam an der Zay) in Austria, dated 5200 BC.
IELTS General Reading Test
Some of the earliest evidence of water wells is located in China. The Neolithic Chinese discovered and made extensive use of deep drilled groundwater for drinking. The Chinese text The Book of Changes, originally a divination text of the Western Zhou dynasty (1046-771 BC), contains an entry describing how the ancient Chinese maintained their wells and protected their sources of water.
Archaeological evidence and old Chinese documents reveal that the prehistoric and ancient Chinese had the aptitude and skills for diggin deep water wells for drinking water as early as 6000 to 7000 years ago. A well excavated at the Hemedu excavation site was believed to have been built during the Neolithic era. The well was surrounded by four rows of logs with a square frame attached to them at the top of the well. 60 additional tile wells southwest of Beijing are also believed to have been built around 600 BC for consumption and irrigation.
IELTS General Reading Test
In Egypt, shadoofs and sakias are used. The sakia is much more efficient, as it can bring up water from a depth of 10 metres (versus the 3 metres of the shadoof). The sakia is the Egyptian version of the noria. Some of the world’s oldest known wells, located in Cyprus, date to 9000-10,500 BC. Two wells from the Neolithic period, around 6500 BC, have been discovered in Israel.
One is in Atlit, on the northern coast of Israel, and the other is the Jezreel Valley. Wells for other purposes came along much later, historically. The first recorded salt well was dug in the Sichuan province of China around 2,250 years ago. This was the first time that ancient water well technology was applied successfully for the exploitation of salt and marked the beginning of Sichuan’s salt drilling industry.
IELTS General Reading Test
Questions 14 – 20
Do the following statements agree with the information given in the Reading Passage?
YES – If the statement agrees with the claims of the writer.
NO – If the statement contradicts the claims of the writer.
NOT GIVEN – If it is impossible to say what the writer thinks about this.
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14. Drawing out water was much easier in the past by using buckets as opposed to using pumps these days.
15. Hand-dug wells are expensive as they are labour-intensive.
16. Hand drilled wells can find water at substantial depths than machine drilled wells.
17. There is no need to filter the well water to make it drinkable as it contains fewer minerals.
IELTS General Reading Test
18. If the methane trickles into water, it can cause ecological issue.
19. Civilizations in the past did not have the talent and capacity for excavating deep water wells for drinking water.
20. Wells were only built to hoard water for drinking purposes
IELTS General Reading Test
Read the text below and question 21-26.
Diodes
A diode is a two-terminal electronic component that conducts current primarily in one direction(Asymmetric conductance); it has low (ideally zero) resistance in one direction, and high (ideally infinite) resistance in the other. A diode vacuum tube or thermionic diode is a vacuum tube with two electrodes, a heated cathode, and a plate, in which electrons can flow in only one direction, from cathode to plate. A semiconductor diode, the most regularly used type today, is a crystalline piece of semiconductor material with a p-n junction connected to two electrical terminals. Semiconductor diodes were the first semiconductor electronic devices.
The discovery of asymmetric electrical conduction across the contact between a crystalline mineral and a metal was made by German physicist Ferdinand Braun in 1874. Today, most diodes are made of silicon, but other semiconducting materials such as gallium arsenide and germanium are also used. The most common function of a diode is to allow an electric current to pass in one direction (called the diode’s forward direction), while blocking it in the opposite direction(the reverse direction). As such, the diode can be viewed as an electronic version of a check valve. This unidirectional behaviour is called rectification and is used to convert alternating current (ac) to direct current (dc).
IELTS General Reading Test
Forms of rectifiers, diodes can be used for such tasks as extracting modulation from radio signals in radio receivers. However, diodes can have more complicated behaviour than this simple on- off action, because of their nonlinear current-voltage characteristics. Semiconductor diodes begin conducting electricity only if a certain threshold voltage or cut-in voltage is present in the forward direction (a state in which the diode is said to be forward-biased).
The voltage drop across a forward-biased diode varies only a little with the current and is a function of temperature; this effect can be used as a temperature sensor or as a voltage reference. Also, diodes’ high resistance to current flowing in the reverse direction suddenly drops to a low resistance when the reverse voltage across the diode reaches a value called the breakdown voltage. A semiconductor diode’s current voltage characteristic can be tailored by selecting the semiconductor materials and the doping impurities introduced into the materials during manufacture.
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These techniques are used to create special-purpose diodes that perform many different functions. For example, diodes are used to regulate voltage (Zener diodes), to protect circuits from high voltage surges (avalanche diodes), to electronically tune radio and TV receivers (varactor diodes), to generate radio-frequency oscillations (tunnel diodes, Gunn diodes, IMPATT diodes), and to produce light (light-emitting diodes). Tunnel, Gunn and IMPATT diodes exhibit negative resistance, which is useful in microwave and switching circuits.
Diodes, both vacuum and semiconductor, can be used as shot-noise generators. In 1874, German scientist Karl Ferdinand Braun discovered the “unilateral conduction “across a contact between a metal and a mineral.Jagadish Chandra Bose was the first to use a crystal for detecting radio waves in1894. The crystal detector was developed into a practical device for wireless telegraphy by Greenleaf Whittier Pickard, who invented a silicon crystal detector in 1903 andreceived a patent for it on November 20, 1906.
IELTS General Reading Test
Other experimenters tried a variety of otherMinerals as detectors. Semiconductor principles were unknown to the developers of these earlyrectifiers. During the 1930s understanding of physics advanced and in the mid-1930s researchers at Bell Telephone Laboratories recognized the potential of the crystal detector for application in microwave technology.Researchers at Bell Labs, Western Electric, MIT, Purdue and in the UK intensively developed point-contact diodes during World War II for application in radar. After World War II, AT&T used these in their microwave towers that criss-crossed the United States, and many radar sets use them even in the 21st century. In 1946, Sylvania began offering the 1N34 crystal diode. During the early 1950s, junction diodes were developed
IELTS General Reading Test
Questions 21 – 26
Write no more than THREE WORDS and/or numbers for each answer.
21. The p-n intersection is coupled with ………… in a semiconductor diode.
22. Gallium arsenide and Germanium are cast-off to make diodes, but ……….. is more common.
23. The main purpose of a diode is to let the current pass in ………. and hindering the opposite current.
24. When the reverse voltage across a diode reaches a breakdown voltage value, diodes’ High resistance to the current flowing in the opposite route abruptly drips to a ……………
25. Greenleaf devised a silicon crystal detector for which he was also bestowed with a ……………… three years later.
26. The development of point-contact diode during a period of war was used for operation in …………………..
IELTS General Reading Test
ANSWERS ARE BELOW
IELTS General Reading Test
ANSWERS
14. NOT GIVEN
15. NO
16. NOT GIVEN
17. NO
18. YES
19. NO
20. NO
21. TWO ELECRICAL TERMINALS
22. SILICON
23. FORWARD DIRECTION OR ONE DIRECTION
24. LOW RESISTENCE
25. PATENT
26. RADAR
IELTS General Reading Test