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Topic: Crookes radiometer

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	Crookes radiometer - Wikipedia, the free encyclopedia
		The radiometer is made from a glass bulb from which much of the air has been removed to form a partial vacuum.
		Crookes incorrectly suggested that the force was due to the pressure of light.
		The first experiment to disprove this theory was done by Arthur Schuster in 1876, who observed that there was a force on the glass bulb of the Crookes radiometer that was in the opposite direction to the rotation of the vanes.
	en.wikipedia.org /wiki/Crookes_radiometer (1604 words)

	Radiometer - TheBestLinks.com - Crookes radiometer, Energy, Quartz, Radiation, ... (Site not responding. Last check: 2007-10-21)
		Radiometer is a device used for measuring and detecting the intensity of radiant thermal energy mainly infrared radiation.
		Radiometer is a partially evacuated glass or quartz tube containing a mounted shaft with four light vanes which are flened on one side and polished metal on the other side.
		When the radiometer is in contact with external radiation the flened side absorbs more heat than the polished side, and the free molecules present in the bulb react more strongly on the dark side than on the light side, thus pushing the dark side away from the source of radiation.
	www.thebestlinks.com /Radiometer.html (181 words)

	Crookes radiometer: Encyclopedia topic (Site not responding. Last check: 2007-10-21)
		The Crookes radiometer was invented by the chemist Sir William Crookes (Sir William Crookes: English chemist and physicist; discovered thallium; invented the radiometer and studied cathode rays (1832-1919)) as the by-product of some chemical research.
		Crookes incorrectly suggested that the force was due to the pressure of light (pressure of light: in acoustics, radiation pressure is the unidirectional pressure force exerted at an interface...
		Finally, if light pressure were the motive force, the radiometer would spin in the opposite direction as the photon (photon: A quantum of electromagnetic radiation; an elementary particle that is its own antiparticle) s on the shiny side being reflected would deposit more momentum than on the fl side where the photons are absorbed.
	www.absoluteastronomy.com /reference/crookes_radiometer (1073 words)

	William Crookes
		Crookes, Sir William 1832-1919, man of science, was born in London 17 June 1832, the eldest son of Joseph Crookes, a tailor of north-country origin, by his second wife, Mary Scott.
		He soon discovered the phenomenon upon which depends the action of the well-known little instrument, the Crookes radiometer, in which a system of vanes, each flened on one side and polished on the other, is set in rotation when exposed to radiant energy.
		For many years Crookes conducted laborious experiments on the elements of the rare earths, elements so similar to one another in chemical properties that special methods for their separation had to be devised.
	www.chem.ox.ac.uk /icl/heyes/LanthAct/Biogs/Crookes.html (1549 words)

	Adventures in CyberSound: Crookes, William (Site not responding. Last check: 2007-10-21)
		Crookes invented the radiometer in 1875 and, beginning in 1878, investigated electrical discharges through highly evacuated "Crookes tubes." These studies laid the foundation for J. Thomson's research in the late 1890s concerning discharge-tube phenomena.
		At the age of 68, Crookes began investigating the phenomenon of radioactivity, which had been discovered in 1896, and invented a device that detected alpha particles emitted from radioactive material.
		Crookes maintained an interest in agriculture and warned in 1898 that the world's population would face starvation unless new fertilizer sources were discovered.
	www.acmi.net.au /AIC/CROOKES_BIO.html (498 words)

	Uv Radiometer
		The Crookes radiometer, also known as the light mill or solar engine, consists of an airtight glass bulb with a set of vanes inside which are mounted on a spindle.
		A Nichols radiometer is the apparatus used by Nichols and Hull in 1901 for the measurement of radiation pressure.
		The reason for the motion of the radiometer was determined by James Clerk Maxwell and Osborne Reynolds in the later portions
	www.frozenup.com /pages9/93/uv-radiometer.html (982 words)

	PIRA Bibliography -
		The fake radiometer is evacuated until the mean free path is about the dimension of the system.
		When the pressure of the Crookes' radiometer is about 1 mm it works well.
		Heat the glass of the radiometer until it is motionless and as it cools it will run backwards.
	physicslearning.colorado.edu /PIRA/PiraSubTOC.asp?STopic=4D20 (253 words)

	William Crookes - TheBestLinks.com - April 4, Chemist, Cathode ray, Crookes radiometer, ... (Site not responding. Last check: 2007-10-21)
		Sir William Crookes (June 17 1832 - April 4 1919) was an English chemist and physicist.
		He was the inventor of the Crookes radiometer, which today is made and sold as a novelty item.
		In his investigations of the conduction of electricity in low pressure gases, he discovered as the pressure was lowered, that the negative electrode appeared to emit rays (the so-called `cathode rays', now known to be a stream of free electrons, and used in cathode ray display devices).
	www.thebestlinks.com /William_Crookes.html (243 words)

	How does a light-mill work?
		In 1873, while investigating infrared radiation and the element thallium, the eminent Victorian experimenter Sir William Crookes developed a special kind of radiometer, an instrument for measuring radiant energy of heat and light.
		Crookes at first believed this demonstrated that light radiation pressure on the fl vanes was turning it round just like water in a water mill.
		To explain the radiometer, therefore, one must focus attention not on the faces of the vanes, but on their edges.
	math.ucr.edu /home/baez/physics/General/LightMill/light-mill.html (1520 words)

	UM Physics Demonstration
		The Crookes' radiometer is a rotator with vanes on it, placed on a free shaft in a glass bulb which has not been evacuated.
		Place the radiometer in the object area of the lantern slide projector.
		When the vanes are illuminated, the assembly rotates away from the fl sides since this surface heats up more so the molecules colliding with it are given a higher recoil velocity, and thus impart more momentum to the vanes.
	www.physics.lsa.umich.edu /demolab/demo.asp?id=186 (87 words)

	Science Museum London - Treasures (Site not responding. Last check: 2007-10-21)
		The radiometer was devised by William Crookes in 1875, while investigating physical effects in a high vacuum.
		With its vanes rotating without apparent cause when placed in the light, the Crookes radiometer remains a popular scientific toy.
		Crookes was led to this work by anomalies he had noticed while weighing samples in a vacuum, during experiments to determine the atomic weight of the element thallium.
	www.sciencemuseum.org.uk /on-line/treasure/objects/1920-410.asp (144 words)

	Crooks Radiometer and Otheoscope (Site not responding. Last check: 2007-10-21)
		The Crookes radiometer is well known to the physics student and in science shops as a fascinating toy (Figure 13).
		measured the ‘radiometer force’ and found it to be several orders of magnitude greater than the ‘light pressure’ anticipated by Maxwell.
		Quoting from the original paper, "The fixed copper disc is lampfled on the upper side with the vanes made of mica for the sake of lightness.
	www.globalwarmingsolutions.co.uk /crooks_radiometer_and_otheoscope.htm (371 words)

	Radiometer - Facts from the Encyclopedia - Yahoo! Education (Site not responding. Last check: 2007-10-21)
		Radiometers that function by an increase in the temperature of the device, such as Herschel's thermometer, are called thermal detectors.
		The term radiometer is often used to refer specifically to a type of thermal detector invented by Sir William Crookes (c.1874).
		Because his device was somewhat insensitive and not readily calibrated, it is rarely used today as a scientific instrument.
	messenger.yahooligans.com /reference/encyclopedia/entry/radiomet (410 words)

	Creamer Media's Engineering News Online, South African Industry News :: Electrically Speaking: Terry Mackenzie-Hoy (Site not responding. Last check: 2007-10-21)
		Crookes radiometer is of no use to the ordinary person
		We can say that the laboratory version of a Crookes radiometer is a hollow glass sphere which has the axle inside, with the vanes attached, and the whole thing is about the size of a tennis ball.
		Nope, I think we can say that a Crookes radiometer is not going to enter the alternative-energy stakes just yet.
	www.engineeringnews.co.za /eng/views/columnist/electrical?show=64390 (613 words)

	Howstuffworks "How does a Crookes' radiometer work?"
		A Crookes' radiometer has four vanes suspended inside a glass bulb as you've described.
		When you shine a light on the vanes in the radiometer, they spin -- in bright sunlight, they can spin at several thousand rotations per minute!
		The vacuum is important to the radiometer's success.
	www.howstuffworks.com /question239.htm (180 words)

	I2-01.HTML (Site not responding. Last check: 2007-10-21)
		When they leave the fl side they therefore introduce a greater reaction force on the fl side, producing rotation in the direction of the white side with the fl side trailing.
		The explanation is not nearly as simple as the difference in the momentum of photons when they are absorbed or reflected, or even as simple as the heating effect on the fl side, which absorbs more photons, compared with the white side, which reflects more.
		This appears to be one of those physics devices that is typically explained incorrectly, even in the literature from the supplier that accompanies the radiometer.
	www.physics.umd.edu /lecdem/services/demos/demosi2/i2-01.htm (527 words)

	Crookes Radiometer (Site not responding. Last check: 2007-10-21)
		Description: This radiometer spins in the opposite direction from what theory predicts; the white sides move forward.
		Turn on the light and watch it spin.
		The fake radiometer is evacuated so the mean free path is about the dimension of the system.
	demoroom.physics.ncsu.edu /html/demos/340.html (76 words)

	Making the Modern World - Icons Of Invention - Science - 1820-1880
		William Crookes (1832-1919) devised the radiometer in 1875 while investigating the behaviour of hot bodies in a vacuum.
		This example was made in Crookes' laboratory in 1877.
		His hope that the radiometer would be used to measure heat radiation was not fulfilled, but it remains a fascinating scientific toy.
	www.makingthemodernworld.org.uk /icons_of_invention/science/1820-1880/IC.035 (162 words)

	Flights of Fancy... - Radiometers
		A hand-blown hanging version of the classic Crookes radiometer, powered by light from G.W. Schleidt.
		Can be hung by itself or chained with other radiometers.
		A hand-blown version of the classic Crookes radiometer, powered by light from G.W. Schleidt.
	www.flightsoffancylv.com /catalog/index.php?a=5&b=411 (231 words)

	Crookes Radiometer (Site not responding. Last check: 2007-10-21)
		Invented by the Victorian scientist Sir William Crookes in 1873, the working of the device was not correctly explained for 6 years and some of the common wrong explanations are still widely quoted as the right answer.
		I have had my Crookes Radiometer in my living room cabinet for about 20 years.
		It needs to be hidden away from people who smash glass by accident on a regular basis!
	nomoresocks.newscientist.com /products/product/37/CrookesRadiometer.htm (411 words)

	CROOKES RADIOMETER
		AIM: To demonstrate a sensitive detector of thermal radiation.
		DESCRIPTION: The radiometer consists of four light mica vanes flened on one side and silvered on the other and arranged on a common pivot so that they may rotate freely in a horizontal plane.
		The glass container is evacuated to a pressure of approximately 10 mm of mercury.
	www.ph.unimelb.edu.au /staffresources/lecdem/he1.htm (135 words)

	Curious Minds - Articles - Physics in Motion - Crookes' Solar Radiometer (Site not responding. Last check: 2007-10-21)
		Curious Minds - Articles - Physics in Motion - Crookes' Solar Radiometer
		Curious Minds » Catalog » Physics in Motion » Crookes' Solar Radiometer
		A measurement of the speed of its rotation can, however, be obtained using a spinning slotted disk, which functions as a strobe light does.
	curiousminds.co.uk /Radiometer (1135 words)

	LIBRARY INSTRUCTION - NATS 102 - LARSON (Site not responding. Last check: 2007-10-21)
		William Crookes, cartoon by Spy from Vanity Fair, 1903.
		Asimov's biographical encyclopedia of science and technology : the lives and achievements of 1510 great scientists from ancient times to the present chronologically arranged.
		RADIOMETER - from the Universidade de Coimbra (Portugal) - Departamento de Fisica - !http://www.fis.uc.pt/museu/149ing.HTM
	dizzy.library.arizona.edu /users/critzl/NATS102LARSON.html (720 words)

	Strobbed Crookes Radiometer - Design
		Without warning, I started thinking about a Crookes radiometer this morning.
		childhood with mirrors and radiometers, but no air conditioning.
		One completely new thought (to me) was to illuminate it with LEDs and to
	www.electronicshelp.net /ntopic6854.html (213 words)

	I2-03.HTML (Site not responding. Last check: 2007-10-21)
		PURPOSE: Counterintuitive demonstration of Crookes' radiometer designed to make students understand radiation better.
		DESCRIPTION: Heat the Crookes' radiometer with the heater for about one minute at about one foot distance, so that it spins rapidly.
		When the temperature of the fl side becomes sufficiently below that of the white side the roles are reversed from normal in heating adjacent air, causing more momentum transfer to the white side and rotation in the direction of the fl side.
	jedlik.phy.bme.hu /~hartlein/physics.umd.edu/deptinfo/facilities/lecdem/i2-03.htm (129 words)

	4D20.10 Crookes' Radiometer (Site not responding. Last check: 2007-10-21)
		A radiometer in front of an electric lamp.
		Demo Staff use an outlet with an on-off switch.
		A second radiometer, with a mirrored side, is used to show what happens when fewer photons strike the panes.
	www.ph.utexas.edu /~phy-demo/demo-txt/4d20-10.html (74 words)

	UK radiometer Websites (Site not responding. Last check: 2007-10-21)
		• Radiometer Analytical - Radiometer analytical : manufacturer of pH and ion meter, potentiometric and Karl Fischer titrator, polarograph for trace analysis, potentiostat and impedance meter
		- Suppliers of oceangraphic instruments, including buoys, monitoring devices, radiometers and meteorological systems.
		Splut may use data from the Open Directory Project to provide a fuller search result
	www.splut.co.uk /sub/r/radiometer.html (91 words)

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