Exercise 8. Prove or correct the following with the facts from the text
Unit
Instrumentation
Before we start:
In pairs, answer the following questions:
What measuring instruments do you know? Why do people use them?
Section 1. Measuring Instruments
Word Study
Words and Terms to be remembered
Stopwatches excess
vast range savings
ruler digital
establish essential
relate slide
item adjustable
reference transducer
designate dissipate
shunt resistor vulnerable
coil crucial
access
Exercise1. The above-mentioned words all appear in the text you are going to read:
A). Work with the dictionary and find the transcription and the meaning of the words
B). Practice pronouncing the words
C). Make up the word-combinations of your own using these words
Exercise 2. Read the words correctly and guess their meanings. Consult the dictionary
Electron microscope, accelerator, terminal, meter, energy, peak period, analogue voltmeter, potentiometer, electromagnetic wattmeter, digital multimeter, metrology, information, stimulate, standard object, controlled, analogue multitester, graphical, stimulate technology
Exercise3. Fill in the box with all derivatives. Consult the dictionary
| Noun | Verb | Adjective | Adverb |
| Accelerate | |||
| Communication | |||
| Adjustable | |||
| Safety | |||
| Establish | |||
| Mechanism |
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Exercise 4.Give Russian equivalents of the following words and word-combinations
Access to information, field of sensors, physical quantity, unprecedented role, off-peak, shunt,
interaction between knowledge and reality, connected in series, consumed, pointer, scale, item,
modern instrumentation, current passes through shunt, adjustable voltage divider, pressure coil
Exercise 5.Give English equivalents of the following words and word-combinations
Bнутреннее сопротивление, потребление, падение напряжения, аудиооборудование, распределитель напряжения, аналоговый вольтметр общего назначения, экономия энергии, измерить потенциал энергии, положение стрелки, цепь.
Exercise6. Find the sentences in the text, in which the above-mentioned word-combinations are used and translate them into Russian
Text Study
Exercise7. Read the text A and find the answers to the following questions
1. Why are measuring instruments in great demand?
2. How can measuring instruments be connected with the circuit?
3. What does metering allow in case of electric rates?
4. How may precision voltage references be available?
Text A
Scientists, engineers and ordinary humans use a vast range of instruments to perform their measurements. These instruments may range from simple objects such as rulers and stopwatches to electron microscopes and particle accelerators.A measuring instrument is a device for measuring a physical quantity. Established standard objects and events are used as units, and the process of measurement gives a number relating the item under the study and the referenced unit of measurement.
An ammeter (from Ampere Meter) is a measuring device used to measure the current in a circuit. Electric current is measured in amperes. Instruments used to measure smaller currents, in the milliampere or microampere range, are designated as milliammeters or microammeters.
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The majority of ammeters are either connected in series with the circuit carrying the current to be measured or have their shunt resistors connected similarly in series. In either case the current passes through the meter or through its shunt. Ammeters must not be connected directly across a voltage source since their internal resistance is very low and excess current would flow. Ammeters are designed for a low voltage drop across their terminals, much less than one volt.
An electricity meter, electrical meter, or energy meter is a device that measures the amount of electric energy consumed by a residence, a business, or an electrically powered device. When energy savings during certain periods are desired, some meters may measure the use of power in some interval. “Time of day” metering allows electric rates to be changed during a day, to record the usage during peak high-cost periods and off-peak as well as lower-cost periods.
A voltmeter is an instrument used for measuring electrical potential difference between two points in an electric circuit. In a circuit diagram a voltmeter is represented by the letter V.
A general purpose analogue voltmeter may have accuracy typically better than 1%. Precision voltage references are available based on electronic circuits.
The measuring instrument called a potentiometer is essentially a voltage divider used for measuring electric potential (voltage). It is a three-terminal resistor with a sliding or rotating contact that forms an adjustable voltage divider. If only two terminals are used, one end and the wiper, it acts as a variable resistor or rheostat. Potentiometers may be used to control electrical devices such as volume controls on audio equipment. Potentiometers operated by a mechanism can be used as a position transducer, for example, in a joystick. They are rarely used to control significant power (more than a watt) since the power dissipated in the potentiometer would be comparable to the power in the controlled load.
A wattmeter is an instrument for measuring the electric power (or supply rate of electrical energy) of any circuit in watts. Electromagnetic wattmeter is used for utility frequency and audio frequency power measurements. In case of an overload the ammeter and voltmeter are both vulnerable to overheating. But in the wattmeter, either or even both the current and potential circuits can overheat without the pointer approaching the end of the scale. This is because the position of the pointer depends on the power factor, voltage and current. Thus, a circuit with a low power factor will give a low reading on the wattmeter, even when both of its circuits are loaded to the maximum safety limit. Therefore, a wattmeter is rated not only in watts, but also in volts and amperes.
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A typical wattmeter in educational labs has two voltage coils (pressure coils) and a current coil. Two pressure coils can be connected in series or parallel to each other to change the ranges of the wattmeter. Another feature is that the pressure coil can also be tapped to change the meter’s range. If the pressure coil has a range of 300 volts, the half of it can be used so that the range becomes 150 volts.
1920s pocket multimeter
A multimeter or a multitester, also known as a VOM (volt-ohm-milliammeter), is an electronic measuring instrument that combines several measurement functions in one unit. A typical multimeter can measure voltage, current and resistance. Analogue of multimeter uses a microammeter with a moving pointer to display readings. Digital multimeters have a numeric display and may also show a graphical bar representing the measured value. Digital multimeters are now more common due to their cost and precision, but analogue multimeters are still preferable in some cases, for example in case of monitoring a rapidly varying value.
The development of the metrology shows that the access to the information, facts and measurements, all crucial to the interaction between knowledge and reality, also serve to stimulate technological innovation. Making use of the latest technology in the fields of sensors, measurements, communication, signal processing and information, modern instrumentation plays an unprecedented role in progress and science.
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Exercise 8. Prove or correct the following with the facts from the text
1. A VOM (volt-ohm-milliammeter), is an electronic measuring instrument that combines several measurement functions in several units.
2. The development of the metrology serves to stimulate technological achievements.
3. A typical wattmeter in labs has two power coils (pressure coils) and a current coil.
4. Potentiometers may be used to control electrical devices on audio equipment.
5. The majority of ammeters are connected parallel with the circuit.
6. Digital multimeters are now more traditional due to their cost and precision.
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