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Also known as Johnson-Nyquist noise, thermal noise is caused by the agitation of electrons inside a conductor, such as copper or aluminum electrical wire. Noise temperature is the resistance, measured in ohms, of the electrons as they travel along the conductor. Thermal conductivity is the rate at which heat transfers across a given material and is measured in degrees kelvin. The ratio of thermal conductivity to noise temperature is a concern; conductivity decreases as velocity increases, because the random movement of the electrons impede themselves from moving forward along the conductor.
An oven has an average life expectancy of 14 years, but, according to the National Association of Home Builders, this number varies based on installation, maintenance and usage. Over a period of time, the oven may not heat to the desired temperature and will require troubleshooting to diagnose and fix the problem. Unlike some appliances that contain sealed components that involve replacing entire segments of the machine, most ovens use easily accessible, individual components that make it easier and less expensive to perform repairs.
A boiler's metal tube will rise in temperature more quickly than the water inside it. Metal's free electrons vibrate quickly with heat, and temperature measures this internal kinetic energy. Water has no such free particles, and hydrogen bonds hold its molecules together, restricting movement. Assuming that heat enters the boiler's tube and water at the same rate during the initial heating stage, you can calculate the tube's final temperature from the temperature rise of the water.
The critical temperature of steel is not a static number. Geological factors can raise or lower the critical temperature. Alloying is one of the most influential factors in determining the critical temperature of steel. Copper, carbon and zinc are alloying elements that will lower the critical temperature of steel. To calculate the critical temperature of steel, it is vital to know the composition and grade of the steel. Contact with alloying elements needs to be identified. If the steel is not pure and contains or is exposed to these alloying elements, critical temperature calculations can widely vary. The percentage of…
Civil engineers sometimes must determine the slagging and fouling behavior of their coal by heating its ash residue in a furnace. Temperature readings are taken at four critical points during the fusion, and these temperatures indicate the usability of the coal. For example, if the coal ash has a low deformation temperature, it may not be suitable for a steam power application.
Personal computers use an intricate network of metallic connections to send billions of electrical signals, which are converted to information. The information can then be displayed on a screen or sent to another system across the world. The electrical charges flowing through the components of a computer cause heat to build up, causing damage to the computer if not cooled. Components in a computer case have a maximum operating temperature beyond which they will cease to function. You can calculate the case temperate in a few steps.
Height, temperature and lapse rate are all related. If you have any two of these numbers, you will be able to figure out the third. The most common lapse rate used is referred to as the environmental lapse rate (ELR). According to Yochanan Kushnir of Colombia College, the relationship between these three variables can be expressed as: ELR = - (dTemperature / dHeight) To calculate temperature or height using the ELR, plug the information you know into the equation, and solve for the unknown variable.
A psychrometric chart is a graph that illustrate the physical and thermal properties of moist air. You need to understand how a psychrometric chart works in order to visualize the concept of how heated air holds more moisture than cool air and as air cools condensation occurs. The psychrometric chart contains dry-bulb temperature scale on the horizontal axis, humidity ratio scale on the vertical axis and a curved boundary to represent saturated air or 100 percent moisture holding capacity. In order to diagnose air temperature and humidity problems, you must also understand how the psychrometric chart works.
The sun, like all stars, primarily behaves as what's called a "blackbody." A blackbody is an object that absorbs all the electromagnetic energy that hits it, then redistributes it and emits its own light. A blade of grass, for example, looks green because it reflects some of the light that hits it. A blackbody looks black because it doesn't reflect any light. But that doesn't mean it doesn't emit its own radiation -- in visible light or at infrared wavelengths. It does, and the spectrum of that radiation depends only on its temperature.
Global warming, which is the rise in the average temperature of the Earth's air and water, has created serious concern among environmentalists. Scientists and policymakers review figures relating to the temperature change of the Earth over time to provide evidence for and against global warming and to make policy decisions. To get this temperature figure right, scientists use a complicated methodology to determine the temperature change of the Earth.
The resistance of an object is the opposition to the flow of electric current through it. There are two factors that influence this property and they both depend on the material's temperature. The resistance of most conductive materials increases as they get hotter but a few become better conductors because their resistance drops when they heat up.
At the time of publication, there are about eight year's worth of helium left at the world's largest helium reserve in Amarillo, Texas, based on the world's current rate of usage. The U.S. supplies 30 percent of the world's helium supply from the Federal Helium Reserve. This helium shortage will affect a wide range of helium applications. Helium is a component of natural gas, so methods for extracting helium from the earth are the same methods used in mining natural gas.
Octane is a molecule with the chemical formula C8H18. This colorless hydrocarbon is one of the many found in the mixture called gasoline. Like other components of gasoline, it's highly flammable and, when heated to high temperatures, will ignite. With a little basic chemistry knowledge, you can calculate how much oxygen is needed for the complete combustion of octane -- first in moles, which is a unit of amount, then in grams, which are a unit of mass.
Helium, a gas that is lighter than air, allows items such as balloons to take flight and hover. Though not all crafts deserve a little lift, some benefit from having a little height associated with them. Using helium in crafting can result in displays that will have people talking.
Weather temperatures are reported around the world using the temperature scale common to the region. For example, the Fahrenheit temperature scale is common in the United States, while British Commonwealth countries like Australia and New Zealand use the Celsius scale. Scientists working in Antarctica commonly employ the Kelvin scale to measure extremely cold temperatures typical of that continent. Whether you're reading a temperature gauge or looking at weather data, it just takes a few steps to calculate the temperature in any of these scales.
You can calculate the peak wavelength of stars using Wien's displacement law. All objects with a temperature emit a spectrum of electromagnetic radiation based on its temperature. Wein's law relates the temperature of an object to the peak, or most common, wavelength emitted. Electromagnetic radiation exists at various wavelengths, including visible light, infrared and microwaves. Wavelengths measure the distance between crests in a wave. For visible light, the peak wavelength of the radiation determines what color is seen.
Electricity is the flow of electrically charged particles called electrons, and it allows mankind a luxurious existence with lighting, heating and television. As electrons flow through a wire they scatter off the surface and off one another. This scattering leads to a reduction in electron energy, and this phenomenon is generally known as resistance.
Weather on the planet Earth is caused by both the temperature and the air pressure. The temperature and air pressure differs depending on the location, and this causes changes in the weather throughout the planet. Numerous factors play into the differing pressures and why it is hotter in some areas than others.
The Earth's climate has never been static over long periods of time. At certain points in history the planet was warmer, with tropical-type temperatures extending into what are now temperate areas. At other times, the Earth was cooler and the polar ice caps in the form of glaciers also extended south into what are now temperate climates. Scientists use a variety of techniques to determine the past history of the Earth's temperatures.
Helium is the first of the noble gases, elements that exist in a monatomic state due to their innate stability leading to a fundamental lack of need to react with other elements in order to exist in the natural world. Because it exists as a gas at normal temperatures and pressures it can be difficult to calculate the weight of helium without reference to Avogadro's constant and the principle of moles.
The rate of heat flowing through a material is determined by the material's R-value or metric U-value. The R-value is measured in the SI, or System International, units of Kelvin meters squared per Watt, or in imperial units, square foot degrees Fahrenheit hours per British thermal unit. The U-value has the inverse of R-value units, Watts per Kelvin meters squared. The greater the U-value or the lower the R-value, the more conductive the material will be. In conversation, the scale of the value implies which system is being used and units are not given.
Water vapor density or moisture content measures the weight of water vapor contained in a given amount of air. Saturation occurs when the air cannot hold additional water vapor. The temperature of the air will dictate the maximum amount of water vapor possible, or the saturation point. This temperature, at which water vapor must begin to condense into liquid, is called the dew point. Moisture content at saturation can be calculated by first finding the moisture pressure.
Test the efficiency of an immersion heater to determine its cost effectiveness when compared to other heating devices. Immersion heaters consist of an approximately 10-inch-long metal bar connected to a power pack that plugs into a wall socket. When plugged in, the metal bar warms up and transfers heat energy, in joules, to the liquid in which it is submerged (See Reference 1). Since the transfer of energy is not perfect, the immersion heater requires more energy to operate than it can transfer to the liquid, based on its efficiency. Efficiencies are expressed as percentages.
Gibbs free energy is used in chemistry to describe whether or not a reaction will occur spontaneously. We can rely on two things to calculate Gibbs free energy: the increase or decrease of entropy associated with a reaction and the amount of heat required or released by the reaction, also known as the change in enthalpy.
Thermal conductivity computation describes how water conducts thermal, heat or energy activity. Thermal conductivity temperatures are usually given on charts and measuring it yourself is experimental. You can do so with a guarded hot place and initial measurements. You must have the partial derivative of the water temperature and use a specific formula to compute it.
When two ends of an object have different temperatures, heat transfer occurs between the two locations through conduction. Conduction transfers heat energy, in joules, between molecules in a substance by their motion. Heat transfer through a bar depends on the temperature at its ends, the area of its side, the time allowed for transfer, its length and its thermal conductivity. Thermal conductivity quantifies how well a substance conducts heat in units of watts per meter per kelvin. Materials with higher thermal conductivities transfer heat more effectively.
A primer is oligomer (a short polymer) of the nucleic acid (DNA) having a certain sequence of the four nucleotides called Adenine("A"), Cytosine("C"), Guanine("G") and Thymine("T"). The primer sequence is written using the one letter code -- "ACCTTGTTAAGCTGA." Primers are mainly used for the polymerase chain reaction (PCR) that is a molecular biology technique. PCR provides a straightforward way to amplify the amount of DNA to quantities necessary for the protein expression or, for example, for the forensic analysis. The melting temperature is a crucial characteristic of a primer. Primers with melting temperatures in the range from 52 to 58…
Enthalpy and entropy are both terms that relate to thermodynamics. Thermodynamics, which relates to physics and chemistry, deals with the concepts of energy and work. When you study thermodynamics, you're studying the changes in energy that come along with chemical and physical changes. Enthalpy and entropy are both variables that relate to these changes in scientific equations. When you're studying thermodynamics, it can be tricky to differentiate enthalpy and entropy because the words sound so much alike. A thorough understanding of how enthalpy and entropy work will help.
A material's thermal conductivity reflects its ability to transfer heat. The official units adopted by the International System of Units is watts per meter per Kelvin, or W/m.K. Other units in common usage include calories per second per centimeter degree Celsius, or cal/s.cm.C; watts per inch per degree Celsius, or W/in.C; btu per hour per foot degrees Fahrenheit, or btu/h.ft.F; btu per second per inch degrees Fahrenheit, or btu/s.in.F and horsepower per foot per degree Fahrenheit, or hp/ft.F.
Thermal conductivity determines the rate that heat is transferred through an area. Tables exist with thermal conductivities for many commonly used building materials, though it can be calculated for your specific application. For instance, some windows are double paned glass which is usually not listed, but if you can determine variables such as the area of the window and the difference in temperature, then you can calculate the thermal conductivity coefficient. The higher the value, the faster heat will flow through the sheet of glass.
The ability of a material to conduct or transfer heat is called its thermal conductivity. Thermal conductivity varies widely for different materials. Some substances like air have poor thermal conductivity whereas others like copper have excellent conductivity. The standard units for thermal conductivity are watts / (Kelvins meters). If you ever forget these units or need to find them again, you can easily derive them using the equation for thermal conductivity.
Thermal conductivity is a characteristic of a material that represents the amount of heat (in Watts) transmitted through the material with a thickness of one meter due to the temperature change of one degree Celsius. The U value is a related quantity that represents the amount of heat lost per square meter of a material. Thus, the U value characterizes the quality of the thermal insulation of materials used, for example, for walls or windows. The lower U-value corresponds to a material's greater resistance to the heat flow.
Heat transfer occurs between two parts of a fluid at different temperatures. Heat always moves from a hotter to a colder region and is measured in joules. When one side of a water tank is at a higher temperature than the opposite side, heat is transferred by conduction. Conduction involves the sharing of heat by molecules in the water when they bump into each other. How effectively a substance conducts heat is quantified by its thermal conductivity. A higher value indicates a better conductor. For example, the thermal conductivity of water is 0.6, while steel has a value of 50.2.
Thermal conductivity of a material determines how well heat is transferred through that substance. In general, the better a material transmits electricity, the better it also conducts heat. This stems from the fact that more electrons are free to move around inside good conductors, such as metals. For example, copper has a thermal conductivity of 385.0, while concrete has a value of 0.8. Thermal conductivity is measured in units of watts per meter per degree kelvin. The kelvin is a unit of temperature used by scientists and engineers.
In a mixture of air, each gas component has its own percentage of pressure and volume. Each can be calculated using Dalton's Law of Partial Pressures and the Ideal Gas Law. Ideal gases are defined as having an insignificant particle size compared to their volume and a negligent affinity for bonding with other gas particles. Partial pressure can be found using the total air pressure and the mole fraction of the individual gas component in the mixture. One mole is equal to an element's atomic mass in grams, or the total mass of all the protons, electrons and neutrons of…
When you need to remove heat away from a metal, energy must be conducted without the assistance of moving parts. The rate of heat transfer will depend on the temperature gradient, which is the difference in temperature across a distance, and the conductivity of the material. Thermal conductivity is closely related to electric conductivity; in fact, metals make good conductors of electricity and heat because of the mobile nature of their electrons, when compared to nonmetals.
A range is an interval that defines the minimum and maximum values for any set of numbers or for the variation of a particular variable -- a stock price on the market, for example. The percent relative range refers to the percentage ratio of the range to the average value in the set.
All objects with a temperature above absolute zero radiate some energy. As the temperature of an object increases, the amount of radiation it emits also increases, and the average wavelength of the emitted radiation decreases. Some mammals, including humans, can distinguish wavelengths of radiation in the 400 to 700 nanometer range, and perceive them as colors. If we make a few assumptions, it becomes fairly straightforward to calculate the color of light emitted by a hot object based on its temperature.
Static temperature is an important concept in the study of thermodynamics and fluid mechanics, with frequent applications to aerodynamics and engineering. When a fluid is flowing and encounters an object, there will be a point where the velocity of the fluid is zero, known as a stagnation point. The fluid flow that lies tangent to the surface where this occurs is known as a stagnation streamline, and the temperature that lies along this curve is known as the static temperature. This quantity is straightforward to calculate with knowledge of the physical properties of the fluid.
Virtual temperature is a calculation that tells you what the temperature of the air would be if and only if the density and pressure of dry air was the same as the density and pressure of wet air. Meteorologists frequently use the term as a comparison device between a drier climate to a humid climate. The formula uses the current temperature, the mixing ratio and the ratio of the gas constants of air and water vapor.
Degree classification in meteorological terms typically describes the units for temperature in Fahrenheit, Celsius and Kelvin. While Fahrenheit and Celsius are the most common units used to measure temperature, scientists principally use Celsius and Kelvin for their calculations. The point of zero in Kelvin is approximately minus-273 degrees Celsius, conceivably the coldest temperature that exists in our universe.
As a chemistry student, you my have to measure how much helium is in a balloon. You can measure the volume, moles and mass of helium in the balloon by using a series of formulae. Measuring the amount of helium in a balloon helps you determine how many balloons you need to achieve a certain amount of lift or how much you can expect one balloon of a certain volume to lift.
Gibbs free energy is a measurement of the maximum amount of work or energy that can theoretically be extracted from a system. The change in free energy is the work done by a chemical reaction or the work that is done upon the system to initiate that reaction. By determining the change in Gibbs free energy in a reaction, you can predict whether the products or the reactants are thermodynamically favored.
Primers, also known as "oligos," are short strands of nucleotides called oligonucleotides that are used as priming sequences in Polymerase Chain Reactions (PCR). The primers "base-pair" to the ends of the sequence you wish to copy, providing 3'-end attachment sites for incoming nucleotides. An optimal annealing temperature is based upon the composition of the primers and allows for specific base-pairing of the oligos to your sequence of interest. Several methods may be used to compute optimal annealing temperature, or Ta.
Metal wire rods, strands and filaments exhibit resistance values that are based on their metallic composition, cross-sectional area and operating temperature at steady state current flow conditions. The resistance of metallic conductors increases at higher temperatures, which allows for a terminal high temperature with power, in watts, with the nickel-chrome wires used in electric stove elements, for example. Knowing the power flow allows a simple calculation of ohms resistance at a given working voltage, or an approximation of temperature based on comparative resistance values if the type of metal forming the wire is known.
Despite the enormous variation in climates and regional temperatures around the world, scientists use an average temperature for the entire surface of the Earth to measure for atmospheric changes as a whole. Although local temperatures may grow either warmer or cooler from year to year, the overall average temperature of the Earth has been rising over the past century.
The thermal conductivity value of a given material is a statement of its ability to conduct heat energy. Thermal conductivity is not a constant; it varies depending on the temperature and volume of the material. It is generally noted in the SI units (the international scientific standard units, based on the metric system) of Watts per Kelvin per meter.
A British thermal unit (BTU) is defined as the amount of heat required to raise the temperature of 1 pound of water by 1 degree Fahrenheit. To calculate the temperature of a water sample from the BTUs applied to it, you must know the weight of the water and its starting temperature. You can measure the weight of the water using a scale, and the temperature using a Fahrenheit thermometer. Once you have that information, calculating the temperature of the water after applying a known number of BTUs of heat is easy.
In the science of measuring things, "accuracy" refers to the difference between a measurement taken by a measuring tool and an actual value. For instance, a thermometer reading of 60 degrees Fahrenheit when the actual temperature is 62 degrees Fahrenheit is not totally accurate, though it is more accurate than a thermometer reading of 58 degrees Fahrenheit during that same time. The relative accuracy of a measurement can be expressed as a percentage; you might say that a thermometer is 98 percent accurate, or that it is accurate within 2 percent. These percentages are easy to calculate.
You have likely seen a bug walking or a leaf floating on the surface of a pond or puddle; the surface tension of water makes this possible. All liquids contain molecules that can flow around each other. This molecular movement is not completely unrestricted because the molecules of most liquids have electrochemical properties that cause them to attract each other. These attractive forces cause cohesion among the molecules that results in a phenomenon known as surface tension. The standard international unit of surface tension is Newtons per meter (N/m). The surface tension of water is largely temperature dependent and is…
Solids increase in length and width in proportion to the temperature rise. For example, according to Halliday and Resnick's "Fundamentals of Physics," copper increases linearly by a factor of α = 17 x 10^-6 for every degree Celsius it rises in temperature. This factor α is called the "linear expansion coefficient." Wire gauge is a logarithmic measure. Since each 3-gauge step up means a doubling of the wire's cross-section, linear expansion coefficients taken from tables wouldn't generally be valid at temperatures so high as to lead to a jump from one gauge value to the next.
Average daily temperature is a climatic measure used to give the user index as to how warm or cold the weather is at any given time. The average of a group of any numbers is calculated by adding together the numbers and then dividing by the number "count" or number of items in the group. Using an average temperature will "filter" out the variability in temperature that occurs from day to night.
Conductivity is the ability of a solution to conduct electricity. It is dependent on the presence of ions in the solution. Ions are derived from ionic compounds that dissolve in water, such as sodium chloride.
In areas with high humidity, understanding the comfort of exterior conditions can be harder than looking at a thermometer. The air and its moisture content carry sensible heat (heat that increases dry-bulb temperature) and latent heat (heat acquired or removed by transition between the liquid and gas states). Sensible and latent heat affect the perception of temperature. Enthalpy, the sum of sensible and latent heat, is measured by finding the wet-bulb temperature corresponding to the relative humidity and dry-bulb temperature. By understanding the relationship of wet-bulb temperature to relative humidity and dry-bulb temperature, one can better understand how to make…
The display in most calculators uses passive LCD, an abbreviation for "Liquid Crystal Display." These displays incorporate special LCD fluid in a glass container with reactive coatings on the inside surface. When a circuit board designed to drive the calculator's display fires, it excites the LCD fluid and causes it to react with the coating inside the glass container. Depending on the calculator, this process may take place as the display changes, on a predetermined periodic refresh rate, or as is common; in high end devices and newer calculators.
BTU stands for "British Thermal Unit." It is a measurement of heat, and each individual unit represents the amount of heat required to raise 1 lb. of water 1 degree F. Each BTU is equivalent to roughly 252 calories of energy. Calculating BTU requirements is essential for determining the cost of many different types of energy consumption, the most prominent of these being home heating costs.
Calculating degree days is important in calculating certain home or commercial heating or cooling requirements or calculating proper agricultural planting requirements. Regardless of the purpose of the calculation, the process for calculating degree days is the same. The general formula for calculating degree days is: Degree Days = Average daily temperature - Base temperature = (maximum + minimum) / 2 - Base temperature. For this example, assume a base of 50 degrees with a minimum temperature of 45 degrees and a maximum temperature of of 70 degrees.
Thermal conductivity is a part of the heat equation. For one-dimensional steady state conduction, the heat equation reduces to: q = -k(dT/dx); where q = heat flux, dT/dx = temperature gradient and k = thermal conductivity. If the heat flux and temperature gradient can be obtained, then thermal conductivity can be calculated using this equation.
Thermal conductivity is a property of a material that describes how easily that material conducts thermal, or heat, energy. Insulation materials must have a very low thermal conductivity, while materials used in cooking or in heat exchangers must have a very high conductivity. Normally, thermal conductivity is a value that is obtained experimentally and made available on charts or tables, but given the proper initial conditions, you can calculate the thermal conductivity value for a given material.
Kelvin temperatures are the Standard International (SI) units for science. The Celsius scale is also used for science, as well as being the common scale used in most countries. Fahrenheit is the scale commonly used in the United States. Calculating Kelvin (K) temperatures is easy, provided you can remember the formula. As long as you can perform simple division, multiplication, subtraction and addition, you'll quickly arrive at your answer.
