Termokopel

Fungsi Termokopel

Pada dunia elektronika , termokopel merupakan sensor  suhu yang banyak digunakan untuk mengubah perbedaan suhu dalam benda menjadi perubahan tegangan listrik  (voltase). Termokopel yang sederhana dapat dipasang, dan memiliki jenis konektor standar yang sama, serta dapat mengukur temperatur dalam jangkauan suhu yang cukup besar dengan batas kesalahan pengukuran kurang dari 1 °C.

Cara Kerja Termokopel

Pada tahun 1821, seorang fisikawan  Estonia  bernama Thomas Johann Seebeck  menemukan bahwa sebuah konduktor (semacam logam) yang diberi perbedaan panas secara gradien akan menghasilkan tegangan listrik. Hal ini disebut sebagai efek termoelektrik. Untuk mengukur perubahan panas ini, gabungan dua macam konduktor sekaligus sering dipakai pada ujung benda panas yang diukur. Konduktor tambahan ini kemudian akan mengalami gradiasi suhu, dan mengalami perubahan tegangan secara berkebalikan dengan perbedaan temperatur benda. Menggunakan logam yang berbeda untuk melengkapi sirkuit akan menghasilkan tegangan yang berbeda, meninggalkan perbedaan kecil tegangan memungkinkan kita melakukan pengukuran, yang bertambah sesuai temperatur. Perbedaan ini umumnya berkisar antara 1 hingga 70 microvolt tiap derajad celcius untuk kisaran yang dihasilkan kombinasi logam modern. Beberapa kombinasi menjadi populer sebagai standar industri, dilihat dari biaya, ketersediaanya, kemudahan, titik lebur, kemampuan kimia, stabilitas, dan hasil. Sangat penting diingat bahwa termokopel mengukur perbedaan temperatur di antara 2 titik, bukan temperatur absolut.

Pada banyak aplikasi, salah satu sambungan (sambungan yang dingin) dijaga sebagai temperatur referensi, sedang yang lain dihubungkan pada objek pengukuran. Termokopel dapat dihubungkan secara seri satu sama lain untuk membuat termopile, dimana tiap sambungan yang panas diarahkan ke suhu yang lebih tinggi dan semua sambungan dingin ke suhu yang lebih rendah.

Dengan begitu, tegangan pada setiap termokopel menjadi naik, yang memungkinkan untuk digunakan pada tegangan yang lebih tinggi. Dengan adanya suhu tetapan pada sambungan dingin, yang berguna untuk pengukuran di laboratorium, secara sederhana termokopel tidak mudah dipakai untuk kebanyakan indikasi sambungan lansung dan instrumen kontrol. Mereka menambahkan sambungan dingin tiruan ke sirkuit mereka yaitu peralatan lain yang sensitif terhadap suhu (seperti termistor atau dioda) untuk mengukur suhu sambungan input pada peralatan, dengan tujuan khusus untuk mengurangi gradiasi suhu di antara ujung-ujungnya.

Di sini, tegangan yang berasal dari hubungan dingin yang diketahui dapat disimulasikan, dan koreksi yang baik dapat diaplikasikan. Hal ini dikenal dengan kompensasi hubungan dingin. Biasanya termokopel dihubungkan dengan alat indikasi oleh kawat yang disebut kabel ekstensi atau kompensasi. Tujuannya sudah jelas. Kabel ekstensi menggunakan kawat-kawat dengan jumlah yang sama dengan kondoktur yang dipakai pada Termokopel itu sendiri. Kabel-kabel ini lebih murah daripada kabel termokopel, walaupun tidak terlalu murah, dan biasanya diproduksi pada bentuk yang tepat untuk pengangkutan jarak jauh - umumnya sebagai kawat tertutup fleksibel atau kabel multi inti. Kabel-kabel ini biasanya memiliki spesifikasi untuk rentang suhu yang lebih besar dari kabel termokopel. Kabel ini direkomendasikan untuk keakuratan tinggi. Kabel kompensasi pada sisi lain, kurang presisi, tetapi murah.

Mereka memakai perbedaan kecil, biasanya campuran material konduktor yang murah yang memiliki koefisien termoelektrik yang sama dengan termokopel (bekerja pada rentang suhu terbatas), dengan hasil yang tidak seakurat kabel ekstensi. Kombinasi ini menghasilkan output yang mirip dengan termokopel, tetapi operasi rentang suhu pada kabel kompensasi dibatasi untuk menjaga agar kesalahan yang diperoleh kecil. Kabel ekstensi atau kompensasi harus dipilih sesuai kebutuhan termokopel. Pemilihan ini menghasilkan tegangan yang proporsional terhadap beda suhu antara sambungan panas dan dingin, dan kutub harus dihubungkan dengan benar sehingga tegangan tambahan ditambahkan pada tegangan termokopel, menggantikan perbedaan suhu antara sambungan panas dan dingin.

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Anemometer

Function Anemometer

Observation of the elements of weather and climate requires meteorological tools that are sensitive, robust, simple and precise. Judging from the way the readings, meteorological equipment consists of two types, namely:

Recording is a tool that can record data continuously, since the installation until the turn of the next tool. Example: barograf and anemograf.

Non recording tool that is used when data must be read at certain times to obtain the data. Example: barometer, and anemometer ermometer.

Anemometer is a device used to measure wind speed and direction. Meteorological unit of wind speed is Knots (Beaufort Scale). While the meteorological unit of wind direction is 0o - 360o and direction of the wind. Anemometer should be placed in open areas.

At the time of the wind, baling-baling/mangkok contained on the anemometer will be moving in the direction of the wind. The greater the wind speed blowing bowls are, the faster the speed of rotation of the disc bowls. Of the number of revolutions in one second it can be seen the wind speed. Anemometer at the counter there is a tool that will calculate the wind speed. The results obtained enumerator recorded instrument, then matched with Beaufort.c Scale Figure Anemometer is:

Type Anemometer

Anemometer itself there are two general types. Types are as follows:

a. Anemometer with three or four bowls

The sensor consists of three or four fruit bowl mounted on a radius centered on a vertical axis or all of the bowl is mounted on a vertical axis. The whole bowl is facing a circumferential direction so that when the wind blows the rotor rotates in the direction fixed. Rotational speed of the rotor depends on wind speed. Through a mechanical system of gears, rotor rotation rate of accumulation systems regulate the distance the wind pointer. Anemometer type "cup counter" can only measure the average wind speed over a period of observation. With this tool, the addition of value that can be read from one observation to the next observation, stating the accumulated mileage of wind during the time of the second observation, so that the wind speed is equal to the accumulated distance traveled divided by time interval of the observations.

b. Thermal Anemometer

This anemometer is a sensor used to measure the velocity of a fluid (air) shortly. The workings of this sensor is based on the amount of the convective heat loss from the sensor to the environment around the sensor. The amount of heat transferred from the sensor is directly related to the fluid velocity passing through the sensor. If only the fluid velocity is changed, then the heat loss can be interpreted as the fluid velocity. Anemometer work follows the principle of pitot tube, which is calculated from the static pressure and velocity pressure.

Anemometer Measurement Process

The following example of a simple calculation of the wind velocity measured by three cup anemometer. Long circular arrangement of bowls is 3 m, and the composition at a time rotating it 20 times in 10 seconds, then the wind speed can be calculated: [(20x3) / 10 m = 6 m / s]

To facilitate the counting rotation of the disc then one cup anemometer was given another color.

Because of differences with respect to wind speed from a variety of different heights, then the installation of the anemometer height is usually adapted to the purpose or usefulness. For fields with a height sensor mounted agroklimatologi (bowl) 2 meters above ground level. To collect supporting data for the Class A pan evaporation measurements, anemometer mounted as high as 0.5 m. In general, the airfield installation height of 10 m. Listed open area at stake that is strong enough. For the purposes of navigation tools should be installed at a distance of 10 x height barrier factors such as a building or tree. Most of the Anemometer is generally not able to record wind speeds below 1-2 miles / hour because there is friction factor of what the early rounds.

Anemometer calibration process

Anemometer calibration process is done periodically in order perfomansi and recording the results remained stable and good. The following sequence on the anemometer calibration process.

For wind direction calibration, the method can yield Following an accuracy of ± 5 ° or better if carefully done. Begin by connecting the instrument to a signal conditioning circuit the which indicates wind direction value. This may be an indicator of the which displays wind direction values ​​in angular degrees or simply a voltmeter monitoring the output. Hold or mount the instrument so the vane center of rotation is over the center of a sheet of paper the which has 30 ° or 45 ° crossmarkings. Position the mounting theinstrument so crossarm is oriented north-south with the vane on the north and the anemometer on the south. With the counterweight pointing directly at the anemometer the wind direction signal should correspond to 180 ° or due south. Looking from above, visually align the vane with each of the crossmarkings and Observe the indicator display. It should correspond to vane position within 5 °. If not, it may be Necessary to adjust the relative position of the vane skirt and shaft. See step 3 in the MAINTENANCE section under potentiometer replacement.

It is Important to note That while the sensor mechanically rotates through 360 °, the full scale wind direction signal from the signal conditioning Occurs at 352 °. For example, in a circuit where 0 to 1:00 VDC represents 0 ° to 360 °, the output must be adjusted for 0978 VDC when the instrument is at 352 ° full scale. (352 ° / 360 ° 1:00 X volts = 0978 volts).

Wind speed calibration is determined by the cup wheel turning factor and the output characteristics of the transducer. Calibration Formulas showing cup wheel rpm and output frequency vs. wind speed are included below.

Calibration Formulas for Model 03 102 Wind Sentry Anemometer

WIND SPEED RPM vs CUP WHEEL

m / s = (0.01250 x rpm) + 0.2

knots = (0.02427 x rpm) + 0.4

mph = (rpm x 0.02795) + 0.4

km / hr = (0.04499 x rpm) + 0.7

WIND SPEED vs OUTPUT FREQUENCY - Hz

m / s = (0.7500 x Hz) + 0.2

knots = (1.4562 x Hz) + 0.4

mph = (1.6770 x Hz) + 0.4

km / hr = (2.6994 x Hz) + 0.7

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Termometer Digital

Digital Thermometer Functions
A thermometer is one measure that serves to determine the temperature of the object (the object / body).
The working principle of Digital Thermometers
Digital thermometer, usually using a thermocouple as a sensor for reading the resistance value changes. Simply put the thermocouple in the form of two wires of different metals that end, only the tip alone, together (welded). The point of this convergence is called hot junction. The principle works utilizing the characteristics of the relationship between voltage (volts) with temperature. Any type of metal, at a given temperature have certain voltage as well. At the same temperature, the metal A has a different voltage to the metal B, there was a voltage difference (small, millivolts) which can be detected. So the input temperature of the environment after the thermocouple is detected as a difference in voltage (volts). This voltage is then converted back to the current value through pengkomparasian with reference values ​​and the offset value in the comparator, its function is to translate each unit into the unit volt ampere then used as a temperature scale that is displayed through the display / monitor in the form of seven segments that show the temperature detected by the thermocouple .

These thermocouples vary, depending on the type of metal used. Type of metal will determine the temperature range that can be measured (thermocouple temperature (low temperature) differs from the thermocouple to measure the temperature of the furnace fuel (high temperature)), as well as sensitivity.
In detail the working principle of a digital thermometer can be explained as follows:
Sensory form of PTC or NTC with a high level of sensitivity will change the value of the prisoner if there is a temperature which prubahan about it.
This resistance value changes linearly with changes in flow, so the value of this current can be converted into the form view display
Before being converted, the value of this current in comparison with the reference value and the offset value in the comparator, its function is to translate each unit volt ampere into the unit which will be converted to display.
Digital thermometer readings Measurement

Reading of thermometer measurements are performed directly from the display with respect to the existing line segment.
Digital Thermometer Calibration

Regular calibration using manual or automatic calibration, manual calibration temperature sensor which is subject to the actual heater temperature from 0 degrees to ofsetnya setting. Automatic calibration consists of heating temperature and the gain in circuit checker for komparatornya
Composer Material Digital Thermometer

Penyususn digital thermometer has a most important part. Constituent materials are as follows:

Sensor PTC / NTC
Comparator (OP-amps and the like)
Analog to Digital converter
Decoder display (eg TTL IC 7447)
Display (7 segment, LCD, monitor)

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Termometer Air Raksa

Mercury thermometer function
The thermometer is a device for measuring temperature. Thermometer analog thermometer can also be called as a manual, because the way the reading

still manual. The use of mercury as the main ingredient thermometer because the mercury expansion coefficient relatively constant so that changes in volume due to increase or decrease in temperature is almost always the same. But there are also some families thermometer contains alcohol with the addition of red dye. Thermometer is safer and easier to read.]

A special type of mercury thermometers, called a maximum thermometer, working with the valve on the neck of the tube near the bulb. When the temperature rises, the mercury is pushed upwards by the force through the expansion valve. When the temperature drops of mercury retained in the valve and can not return to the bulb to keep the mercury in the tube. The reader can then read the maximum temperature for a predetermined time. To restore its function, the thermometer should be swung hard. This thermometer medical thermometer-like design.

Mercury will freeze at a temperature of -38.83 ° C (-37.89 ° F) and can only be used at temperatures above it. Mercury, unlike water, does not expand when frozen so it does not break the glass tube, making it difficult to observe when it freezes. If the thermometer contains nitrogen, the gas may flow down into the column and trapped there when the temperature rises. If this happens the thermometer can not be used to return to the initial conditions. To avoid this, the mercury thermometer should be put in a warm place at temperatures below -37 ° C (-34.6 ° F). In the area where the maximum temperature is expected to rise above - 38.83 ° C (-37.89 ° F) thermometer that uses a mixture of mercury and thallium may be used. This thermometer has a freezing point of -61.1 ° C (-78 ° F).

Measurement of Mercury Thermometers

Generally use a mercury thermometer scale Celsius temperature and Fahrenhait. Celsius used two important points on the scale: the temperature when the ice melts and the water evaporation temperature. Ice melt at the same calibration mark on the thermometer in the steam of boiling water. When the thermometer out of water vapor, the height of the mercury down slowly. This relates to the rate of cooling (and the expansion of the glass tube). So pegukuran celsius temperature using the temperature of melting and freezing temperatures are not.

Celsius is the boiling point of 0 ° C (212 ° F) and freezing at 100 ° C (32 ° F). But other researchers, Frenchman Jean Pierre Cristin proposed version of the reverse-Celsius scale the freezing point at 0 ° C (32 ° F) and boiling at 100 ° C (212 ° F). He named it Centrigade.

The workings of Mercury Thermometers

This device consists of a capillary tube using a glass material containing mercury at the lower end. For measurement purposes, the pipe is made in such a way that the vacuum. If the temperature increases, the mercury will expand up to the top of the pipe and provide clues about the temperature gauge in accordance with a predetermined scale. The general way of working is as follows;

Prior to the change in temperature, the volume of mercury is in the initial conditions.
Temperature changes in the environment around the mercury thermometer responded with volume changes.
The volume of mercury will expand if the temperature increases and will shrink when the temperature decreases.
The scale of the thermometer will indicate the temperature corresponding state of the environment.

Calibration Mercury Thermometers

Calibration is the process of verifying that an accuracy of measuring instruments in accordance with the design. Calibration is usually done by comparing a standard that is connected with national and international standards and certified reference materials.

Thermometer calibration process include:

Place the thermometer in the water cylinder is being melted and check points around the thermometer when the liquid water entirely. This point is the freezing point of water.
In the same way, mark the point when the thermometer throughout the entire boiling water when heated.
For the length of the above two points into one hundred equal parts.

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BOYLE LAW

CHAPTER I

INTRODUCTION

A. Background

Gas is a substance which molecules or particles move freely. in this chapter will be studied on the microscopic properties of a gas with a review of the pressure, volume and temperature is often called the kinetic theory of gases. otherwise it will be studied also the science of energy is often called thermodynamics, which specifically discusses the relationship between heat energy to work. energy can be transformed from one form to another, either naturally or the result of engineering technology. besides the energy in the universe is eternal, can not be raised or eliminated, what happens is a change of energy from one form into another form without any reduction or increase. it is closely connected with the law - the basic law of the thermodynamics.

B. Problem formulation

Then the problem is formulated as follows:

What is the ideal gas equation of kinetic theory?

What is the sense and the laws of thermodynamics?

C. Purpose

writing of this paper are expected to provide the following benefits:

Provide additional knowledge to the reader about the ideal gas equation of kinetic theory.

Provide an explanation of things - the basic thing that is often overlooked in thermodynamics.

Provide knowledge and understanding to the reader about the laws of thermodynamics.

CHAPTER II

DISCUSSION

A. Kinetic Theory of Ideal Gas

In this case the so-called ideal gas is a gas that meets the following assumptions:

Consists of particles in large numbers and no force of attraction antarpatikel

Each gas particle is always moving in random directions (arbitrary)

Negligible particle size to the size of the container

Each collision is occurring perfectly resilient.

Gas particles distributed uniformly in the entire space in the container.

Motion of gas particles meet newton laws of motion.

Based on the experimental equation of state of gas that has been done by changing the amount of pressure, volume, and temperature was no proportionality between the product of pressure and volume to temperature as follows:

PV? T

as well as the mass of the gas system after varied with the pressure, volume, and temperature of proportionality are as follows:

PV? MT

to make the above equation to be perfect it would require a constant comparison of equal value to all gas. of the experimental results of the constant comparison is different for each gas if we use mass units but using mol. 1 mole is defined as the amount of substance contained in 12 grams of carbon-12 atoms which is about 6.02 x 1023 particles. 6.02 x 1023 numbers called numbers avogrado (na)

mole of a substance can thus be expressed in the number of particles n as follows:

n = or n = n na

with

n = amount of substance (mol)

n = number of particles (molecules)

na = number avogrado (6.02 x 1023)

universal constant of proportionality, which applies to all gas is r (universal gas constant) so that the ideal gas equation of state can be written as follows widened.

PV = nRT

with

p = gas pressure (atm or N/m2)

v = volume of gas (m3 or liter)

n = number of moles of gas (mol)

r = the universal gas tetapam (8.31 j / mol k)

t = temperature of gas (k)

therefore n = the ideal gas equation of state can be expressed in a number of molecules.

pv = rt

pv = NKT

with Boltzmann constant k == (1.38 × 10-23 j / k)

p = gas pressure (N/m2)

v = volume of gas (m3)

n = number of molecules

t = temperature of gas (k)

when viewed from a microscopic point of view, the particles exert a force of mutual attraction of substances derived from the electrical properties and gravity (Newton's law of gravity). in addition there is also a pull force antarpartikel antarpartikel repulsive force emanating from the electrical properties of atomic nuclei are positively charged. atomic mass centered on the nucleus, so Juka atomic distances are too close there will be a significant repulsive force of the atoms. thus, there is a minimum distance that must be maintained by the atoms in order to avoid the repulsive force.

ideal gas equation of state

ideal gas equation is an equation that menyetakan relationship between pressure, volume, and temperature of a gas. The following equations are found in the laws of physics.

Boyle's law

Boyle's law which says if the mass and temperature of a gas is kept constant then the volume of gas will be inversely proportional to absolute pressure, which is proposed by Robert Boyle (1627-1691).

caption =

Another statement of Boyle's law is that the time between pressure and volume will be a constant value for the mass and the gas temperature is maintained constant. can be written mathematically

pv = c

caption =

gas pressure p = (n / m 2 or pa)

v = volume of gas (m3)

c = constant is dimensionless business

examples of questions

contained in a 4 liter container of gas with a pressure of 4 atm and a temperature of 470c. then the gas pressure to 1/4 of its original pressure and gas temperature is maintained constant. what is the volume of gas now?

discussion:

p1 = 4 atm of Boyle's law, at fixed temperature relationship

¼ p1 = p2 = 1 atm applies are: p1.v1 = p2.v2

t = 470c v2 ==

v1 = 4L = 16 liters

v2 = ....? so, now is the gas volume of 16 liters.

charles law

charles law reads gas volume is directly proportional to absolute temperature, during the mass and the gas pressure is maintained constant, expressed by jacques charles 1787. thus the volume and temperature of a gas at constant pressure is directly proportional and the proportionality can be written mathematically as follows.

v = kt, where k is a constant

then to the gas in a container volume and temperature changes from state 1 to state 2 when the pressure is maintained constant and mass, can be formulated following:

=

by v1 = initial volume of gas (m3)

v2 = final gas volume (m3)

t1 = initial gas temperature (k)

t2 = final gas temperature (k)

examples of questions

gas in an enclosed space has a volume of 1 liter at a pressure of 10 atm and temperature of 470c. gas is heated at a constant pressure so that the temperature be 770c. what is the volume of gas now?

discussion

p = 10 atm at a constant pressure force relationship as follows.

v1 = 1l =

t1 = 470c = 320 k = 1.094 liter è == v2

t2 = 350 k = 770c so, now is the gas volume of 1.094 liter

Gay Lussac law

at constant volume, gas pressure is directly proportional to absolute temperature of the gas. relationship is known as Gay-Lussac's law, expressed by joseph gey Lussac (1778-1850). mathematically written as follows:

or p = c.t

= C ===> v = fixed

for gas in a container that had kept warm by volume, at the 1 and 2 gey Lussac law can be written as follows:

====> V = fixed

with p1 = initial pressure (atm)

p2 = the final pressure (atm)

t1 = initial absolute temperature (k)

t2 = final temperature (k)

examples of questions

gas in an enclosed space has a volume of 2.5 liters, 2 atm pressure, and temperature of 270c. what is the gas pressure if the temperature is increased to 670c in fixed volume?

discussion:

v = 2.5 l in volume gey Lussac law remains in force,

p1 = 2 atm ===> p1 == p2 => p2 = x 2

t1 = 270c = 300k p2 = 2.27 atm

t2 = 670c = 340K so, the gas pressure at a temperature of 670c is 2.27 atm

Boyle-Gay Lussac law

a formula derived from the development of the law of Boyle and Gay Lussac equation of state of gas is a more general scale connecting pressure, volume, and temperature in various keadaaa, so as to obtain the following equation:

= C if the two states then can be written as =

information

p1 = initial gas pressure (N/m2)

v1 = initial volume of gas (m3)

t1 = the absolute temperature of gas at first (k)

p2 = the final gas pressure (N/m2)

v2 = final gas volume (m3)

t2 = the absolute temperature of the end gas (k)

examples of questions

the density of a gas at temperature T and pressure p is p. if the gas pressure is used as the 2p and the temperature was lowered to 0.5 t. determine the density of the end?

discussion:

p1 = p

p2 = 2p

t1 = t

t2 = 0.5 t

v1 =

v2 =

theory of thermodynamics

on the thermodynamics of the process there are four isobaric, isothermal, iskhorik, adiabatic. these processes are used in the law of thermodynamics i.

isobaric process (constant pressure)

in the isobaric process, the system pressure be kept constant. because the pressure is constant, then the energy change in (delta u), heat (q) and work (w) in the isobaric process no one is zero. thus, the equation of the first law of thermodynamics remains intact as before:

gas pressure and volume changes in isobaric process is described by the graph below:

first volume of the system = v1 (small volume). because the pressure be kept constant after the heat added to the system, the system expands and does work on the environment. after doing work on the environment, the volume of the system changed to v2 (the system volume increases). the amount of work (w) is performed by the system = the shaded area.

the isothermal (constant temperature)

in the isothermal process, the system temperature be kept constant, the temperature of an ideal gas is directly proportional to the energy in an ideal gas (u = 3/2 NRT). because t does not change then u is not changed. thus, if applied to the isothermal process, the first law of thermodynamics equation will change shape like this:

of these results, we can conclude that in the isothermal (constant temperature), heat (q) is added to the system used the system to perform the work (w).

pressure and volume changes in the process of isothermal systems described by the graph below:

first volume of the system = v1 (small volume) and the system pressure = p1 (pressure). so that the system temperature constant after the heat added to the system, the system expands and does work on the environment. once the system does work on the environment, the volume of the system changed to v2 (the system volume increases) and the pressure turns into p2 system (the system pressure is reduced). curved graph form as the system pressure does not change regularly during the process. amount of work done = area of ​​the shaded system.

isokorik process (constant volume)

isokorik process, the system volume be kept constant. then the system can not perform work on the environment. vice versa, the environment can not do the work in the system.

if applied to the process isokorik, the first law of thermodynamics equation will change shape like this:

of these results, we can conclude that the process isokorik (constant volume), heat (q) is added to the system used to raise the energy in the system.

pressure and volume changes in the system isokorik illustrated by the graph below:

initial system pressure = p1 (small pressure). the addition of heat to the system causes the energy in the system increases. because the energy in the system increases the temperature of the system (ideal gas) increases (u = 3/2 NRT). temperature is directly proportional to pressure. Therefore, if the system temperature increases, the system pressure increases (p2). because the volume of the system is always constant, there is no work done (no shaded area).

adiabatic process

adiabatic process, no heat is added to the system or leave the system (q = 0). adiabatic process can occur in a closed system that is well insulated. for a closed system that is well insulated, usually with no heat flow into the system arbitrarily or leave the system. adiabatic process can also occur in a closed system is not isolated. for this case, the process must be done very quickly so the heat could not flow into the system or leave the system.

if applied to the adiabatic process, the first law of thermodynamics equation will change shape like this:

if the system is rapidly suppressed (work done on the system), then the work is negative. because w is negative, then u is positive (energy in the system increases). otherwise if the system or expands rapidly expanding (the system does work), then w is positive. because w is positive, then u is negative (energy in the system is reduced).

energy in the system (ideal gas) is proportional to temperature (u = 3/2 NRT), hence if the energy in the system increases, the system also increases. conversely, if the energy in the system reduced the system temperature is reduced.

pressure and volume changes in the adiabatic system described by the graph below:

adiabatic curve on this graph (curves 1-2) is steeper than the isothermal curves (curves 1-3). steepness of this difference suggests that for the same increase in volume, the system pressure is reduced more in the process of adiabatic than isothermal process. system pressure is reduced more in the process adiabatic because when the adiabatic expansion, the temperature of the system is also reduced. temperature is proportional to the pressure, so when the system temperature decreases, the system pressure is also reduced. vice versa in isothermal process, the temperature of the system is always constant. thus the isothermal process the temperature does not influence the pressure drop.

bibliography

hilman, setiawan. 2007.fisika for sma and ma xi class. Dharma kalokatama.jakarta devices.

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Voltmeter

A voltmeter is an instrument that serves to measure the electrical voltage. With the added multiplier tool will be able to improve the ability of the voltmeter measurement tool many times over.

Magnetic force will arise from the interaction between magnetic fields and strong currents. Magnetic style will be able to make a voltmeter gauge needle move when there is an electric current. The greater the electric current, the greater the deviation mengelir needle happens.

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Amperemeter

Ammeter is a device used to measure strong electric current. This tool is generally used by electronics technicians in the electrical appliance tester called multi avometer combination of functions ammeters, voltmeter and ohmmeter.

Ampere meter can be made ​​on the composition mikroamperemeter and shunt functioning on the current detection circuit for either a small current, while for large currents ditambhan the shunt resistance.

Ammeters work according to the Lorentz force magnetic force. Current flowing in the coil's magnetic field would lead to blanket the Lorentz force which can move the needle ammeters. The greater the current flow, the greater the deviation.

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