Intensity Meter

Wiens Law to calculate surface temperature of a star?

The maximum intensity of light from a star occurs at a wavelength of 8.09 x 10-7 meters. Use Wien’s Law to calculate the surface temperature of the star in degrees Kelvin.

Use the law L * T = 2.9*10^-3 approx
L is the wavelength at which the maximum radiation is emitted.

The mass of an object is a measure of the amount of matter present in it and remains constant. The SI unit of mass is the kilogram (kg). The weight of an object varies with the gravitational field of influence. While the SI unit of length is the meter (m), length units on the atomic scale are nanometer (nm) and Picometre (pm). Units volume resulting from the units of length, the largest volume units in chemistry are the cubic meter (m3) and liter (L). Density (d) is the ratio between mass and volume of a substance and one of its physical properties. Temperature is a measure of the relative warmth of an object. Heat is energy flowing of an object above one at a lower temperature. Temperature scales differ in the size of the unit level and / or zero point. The chemistry of the temperature is measured in K (Kelvin), or degrees Celsius (° C). Extensive properties like mass, volume and energy depend on the size of objects (the extension). Properties intensive, such as density and temperature are independent of size. Today is so common measurement that is taken as for granted, but has a long and fascinating history characterized by the pursuit of accurate, unchanging rules.

Measurement system began to thousands of years ago as trade, construction and topography spread through the civilized world. For most of that time, however, the measurements are based inaccurate standards in physics. For example, one inch was the length of three barley grains (seeds) placed end to end a yard was the distance from the tip of the nose King Edgar to the tip of your thumb at arm's length, and one hectare in area cultivated by a man who works with a pair of oxen in a day.

The level meter is now based on two quantities, the speed of light in vacuum and the second. The story points underground to the current unit for defining units based on fast rules. French scientists who created the metric system defines the meter as 1 / 10, 000,000, the distance from Ecuador (in Paris) to the North Pole. The meter was later defined as the distance between the two periods of five lines of engraving on a corrosion resistant metal bar kept in the Office International Weights and Measures in France. The fear that the bar would be destroyed or damaged by the war led to a precise, invariable rule, atomic universally available, 1,650,763.73 wavelengths of red light orange electrically excited atoms of Krypton. The current standard is even more reliable, 1 meter is the distance traveled light in vacuum in 1 / 299, 792.458 seconds.

The U.S. copy per kilo master is stored in a vault in the National Institute of Standards and Technology near Washington, DC since 1889, has been to France twice for comparison with the kilograms teacher who retired from his vault once a year for these purposes. Two people were always there when you move, one to take with tweezers and the other to catch it, if you encounter first hand. The kilogram is rare otherwise, it's just the base unit, whose name has a prefix. Unlike the practice with other basic units, however, attach prefixes to the word "Gram" as in "microgram" instead of the word "kilo". So, never say "micro-kilo".

The SI unit of time is the second (s). Although time was once measured by the day and year, now is based on an atomic standard, microwave, and radiation of the cesium atoms excited. In the lab, we study the reaction rate by measuring the time it takes a fixed amount of substance to undergo chemical change. The range of speeds reaction is enormous, a chemical change in faster in a few nanoseconds (10-9S), while the slow ones, such as oxidation or biological aging, take years. They use lasers to study chemical changes that occur within a few picoseconds (10-12s) or even femto-second (10-15s). The accuracy of the clock pendulum is best for within 3 seconds per year and the best quartz watch is 1000 times greater. The latest version of Atomic Clock NIST-7, has 2000 Sometimes More precisely, within 1 second in 6 million years. Instead of using a pendulum swings, the atomic clock that measures the frequency of oscillation natural cesium atoms absorb microwave radiation. 1 seconds is defined as 9,192,631,770 of these oscillations. Current Plausto the scene of an advanced laser atomic clock cooled cesium in the international space station will allow the times and the observation of atoms, for atleast a 10 fold increase in precision.

About the Author:

Dr.Badruddin Khan teaches Chemistry in the University of kashmir, Srinagar, india.

Article Source: ArticlesBase.com – The Central Importance of Measurement in Science