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Date: circa 1980

Inventory Number: 1998-1-1371a

Classification: Slide Rule

Subject:

Maker: General Electric Company (1892-present)

Cultural Region:

Place of Origin:

Dimensions:

0.4 x 26.7 x 10.1 cm (3/16 x 10 1/2 x 4 in.)

Accessories: with Example Problems Pamphlet (1998-1-1371b)

DescriptionSlide rule designed by General Electric for calculating black-body radiation. The rule consists of a plastic sheath with a card that slides inside the sheath.

The front of the sheath consists of a series of scales with which the emissivity of a body at particular wavelengths can be calculated for any given temperature. The top window displays a temperature scale, Celsius on top, Kelvin on the bottom. Two arrows across from one another, one on top, one on the bottom, point to a reading on the scale. Next down is a custom scale labeled "C" and "D" and ruled logarithmically. The next window down gives the energy flux in Watts per square centimeter, indicated on the top scale of the sliding card, and the energy flux of the maximum wavelength, that is, the maximum on a black body curve for the given temperature, indicated on the bottom scale of the sliding card. The scale above and below correspond to the emissivity of the body, that is, how well the body radiates energy compared to a black body. A perfect black body would have an emissivity of 1, while all other bodies would have an emissivity of less than 1. The flux is given by the value lined up with the emissivity of the object in question. The bottom window gives the energy flux as a function of the wavelength. The sliding card is a scale of wavelengths. The scale above the window compares the emissivity at a given wavelength to the emissivity of the wavelength whose emissivity is a maximum. The scale beneath the window gives the percentage of energy below that is emitted at wavelengths below a given wavelength. A blue line graph runs between the two wavelength scales, and a red line graph runs at the left end of the wavelength scale with labels that indicate which color corresponds to which wavelength.

The back of the slide rule allows for more conversions to other factors. As on the front, the top window gives the temperature, only on this side the temperature is in Fahrenheit and Rankine. A scale next to this gives the number of waves per centimeter. The next scale gives the emissivity, in Watts per square inch on the top, in BTU per square foot per hour on the bottom. The next scale is similar to the temperature scale, in that it has two arrows pointing to readings on the top and bottom scale. The top scale is logarithmic and given in photons per second per square centimeter, while the bottom gives the photon energy at the wavelength of maximum intensity in electron volts. The very bottom window gives the incident energy at a particular range. The scales on the card give the incident energy per square centimeter. The scale above the window gives the distance of the incidence from the source in centimeters, while the scale beneath the window gives the distance in nautical miles. A distance of one kilometer is indicated on each scale.

A yellow box sits on either side of the back of the sheath. The left box gives equations relating to black body radiation: Planck's Equation, Wien's Displacement Law, the Stefan-Boltzmann Law, and the Stefan-Boltzmann Constant in seven different units. The box on the right defines the symbols used in the scales, including W, T, and &lambda, and physical constants, including Planck's constant, Boltzmann's constant, and the speed of light.

The front of the sheath consists of a series of scales with which the emissivity of a body at particular wavelengths can be calculated for any given temperature. The top window displays a temperature scale, Celsius on top, Kelvin on the bottom. Two arrows across from one another, one on top, one on the bottom, point to a reading on the scale. Next down is a custom scale labeled "C" and "D" and ruled logarithmically. The next window down gives the energy flux in Watts per square centimeter, indicated on the top scale of the sliding card, and the energy flux of the maximum wavelength, that is, the maximum on a black body curve for the given temperature, indicated on the bottom scale of the sliding card. The scale above and below correspond to the emissivity of the body, that is, how well the body radiates energy compared to a black body. A perfect black body would have an emissivity of 1, while all other bodies would have an emissivity of less than 1. The flux is given by the value lined up with the emissivity of the object in question. The bottom window gives the energy flux as a function of the wavelength. The sliding card is a scale of wavelengths. The scale above the window compares the emissivity at a given wavelength to the emissivity of the wavelength whose emissivity is a maximum. The scale beneath the window gives the percentage of energy below that is emitted at wavelengths below a given wavelength. A blue line graph runs between the two wavelength scales, and a red line graph runs at the left end of the wavelength scale with labels that indicate which color corresponds to which wavelength.

The back of the slide rule allows for more conversions to other factors. As on the front, the top window gives the temperature, only on this side the temperature is in Fahrenheit and Rankine. A scale next to this gives the number of waves per centimeter. The next scale gives the emissivity, in Watts per square inch on the top, in BTU per square foot per hour on the bottom. The next scale is similar to the temperature scale, in that it has two arrows pointing to readings on the top and bottom scale. The top scale is logarithmic and given in photons per second per square centimeter, while the bottom gives the photon energy at the wavelength of maximum intensity in electron volts. The very bottom window gives the incident energy at a particular range. The scales on the card give the incident energy per square centimeter. The scale above the window gives the distance of the incidence from the source in centimeters, while the scale beneath the window gives the distance in nautical miles. A distance of one kilometer is indicated on each scale.

A yellow box sits on either side of the back of the sheath. The left box gives equations relating to black body radiation: Planck's Equation, Wien's Displacement Law, the Stefan-Boltzmann Law, and the Stefan-Boltzmann Constant in seven different units. The box on the right defines the symbols used in the scales, including W, T, and &lambda, and physical constants, including Planck's constant, Boltzmann's constant, and the speed of light.

Signedfront header: RADIATION / CALCULATOR / courtesy of / LIGHT MILITARY ELECTRONICS / DEPARTMENT / GENERAL ELECTRIC / UTICA, N. Y.

Inscribedfront footer: GEN. 15-B 9-56 (2500) PERCENTAGE INCREMENT OF ENERGY FALLING BELOW ANY WAVELENGTH FOR A BLACK BODY AT TEMPERATURE {T}

on plastic rule: CENTIGRADE (°C) / TEMPERATURE / KELVIN (°K)=(°C+273) / EMISSIVITY / W=WATTS/SQ. CM. / W_{λ max}=WATTS/SQ. CM./MICRON / Δλ AT MAXIMUM / FACTOR OF ENERGY AT MAXIMUM W_{λ max} AT CORRESPONDING WAVELENGTH FOR A BLACK BODY AT TEMPERATURE (T) / W_{λ}/W_{λ max} / λ WAVELENGTH / (MICRONS) / w_{0-λ}/W_{0-∞
rear column 1: PLANCK'S EQUATION: / Wλ = C1λ-5(eC2/λT-1)-1 / WIEN'S DISPLACEMENT LAW: / &lambdam = o/T / STEFAN-BOLTZMANN LAW: / W = ρσT4 or W = ρσ(T4 - T04) / STEFAN-BOLTZMANN CONSTANT (σ) / 5.6686 x 10-5 ergs cm-2deg-4sec-1 / 5.6686 x 10-12 watts cm-2 deg-4 / 1.354 x 10-12 cal cm-2 deg-4 sec-1 / 3.657 x 10-11 watts in-2 deg-4 / 1.797 x 10-8 Btu ft-2 deg-4 hr-1 / 5.267 x 10-12 Kwh ft-12 deg-4 hr-1 / 4.529 x 10-9 Kcal ft-2 deg -4 hr -1
rear second column: SYMBOLS AND PHYSICAL CONSTANTS / Wλ=RADIANT FLUX PER UNIT AREA PER UNIT INCREMENT OF / WAVELENGTH=watts/cm2/cm Δ&lambda or watts/cm2/micron Δ&lambda / W=TOTAL RADIANT FLUX EMITTED PER UNIT AREA / T=ABSOLUTE TEMPERATURE OF RADIATING BODY (°K) / T0=ABSOLUTE TEMPERATURE OF SURROUNDINGS (°K) / λ=WAVELENGTH IN CENTIMETERS OR MICRONS / λm=WAVELENGTH IN MICRONS OF MAXIMA OF BLACK BODY CURVE / ο=CONSTANT FOR BLACK BODY=2897.9 MICRON DEGREES / C1=2πc2h=3.7413x10-12 watt cm2 / C2=hc/k=1.4388 cm degree / e=2.71828 NAPERIAN BASE / ρ=EMISSIVITY FACTOR (BLACK BODY=1) / σ=STEFAN-BOLTZMANN CONSTANT (DEG=K) / c=VELOCITY OF LIGHT=2.99793x1010 cm/sec / =2.99793x1014 micron/sec / h=PLANCK'S CONSTANT=6.6252x1034 watt sec2 / k=BOLTZMANN'S CONSTANT=1.38042x107 watt sec/degree / 1/π=TOTAL RADIANT FLUX PER UNIT SOLID ANGLE (CENTRAL STERADIAN)
rear ruler: FAHRENHEIT (°F) / TEMPERATURE / WAVES/CENTIMETER / (CM-1) EMISSIVITY RANKINE (°R)=(°FA + 460) / WATTS/SQ. IN. / S.T.U./SQ. FT./HR. / EMISSIVITY / PHOTONS/SEC/CM2 / PHOTON ENERGY / AT λ MAX IN / ELECTRON VOLTS / INCIDENT ENERGY IN / WATTS/CM2 FOR 1 CM2 SOURCE AT / INDEX TEMPERATURE RANGE / (CENTIMETERS[sic] / RANGE (NAUTICAL / MILES)}

on plastic rule: CENTIGRADE (°C) / TEMPERATURE / KELVIN (°K)=(°C+273) / EMISSIVITY / W=WATTS/SQ. CM. / W

FunctionTo calculate optical radiation from the UV to the far infrared as a function of temperature, wavelength and emissivity.

The slide rule is based on Planck's equation. Scales correlate temperature, emisivity, 'factor of energy at maximum wavelength at corresponding wavelength for a black body at temperature.' & on the reverse: temperature, waves/centimeter, watts/sq. inch, B.T.U./sq. foot/hour, photons/sec/sq. cm, photon energy, incident energy.

The slide rule is based on Planck's equation. Scales correlate temperature, emisivity, 'factor of energy at maximum wavelength at corresponding wavelength for a black body at temperature.' & on the reverse: temperature, waves/centimeter, watts/sq. inch, B.T.U./sq. foot/hour, photons/sec/sq. cm, photon energy, incident energy.

Curatorial RemarksThere are three essentially identical rules in the collection: 1998-1-1371a, 2001-1-0007 and 2004-1-0383. The only differences between them are:

1) 2004-1-0383 says it it was "compiled by the optics and color engineering component, General Electric Laboratory" whereas the other two say "courtesy of light military electronics department".

2) 2004-1-0383 has ballpen inscriptions

3) on bottom left they are marked as following:

1998-1-1371a: GEN-15-B

2001-1-0007: GEN-15-C

2004-1-0383: GEN. 15-B 9-56 (2500)

1998-1-1371a was originally dated ca.1950, but this was changed to ca.1980 to reflect information of 2001-1-0007, which has the most reliable accession information from its original user.

4) The rules differ in color probably due to differing aging effects ofrom light exposure

1) 2004-1-0383 says it it was "compiled by the optics and color engineering component, General Electric Laboratory" whereas the other two say "courtesy of light military electronics department".

2) 2004-1-0383 has ballpen inscriptions

3) on bottom left they are marked as following:

1998-1-1371a: GEN-15-B

2001-1-0007: GEN-15-C

2004-1-0383: GEN. 15-B 9-56 (2500)

1998-1-1371a was originally dated ca.1950, but this was changed to ca.1980 to reflect information of 2001-1-0007, which has the most reliable accession information from its original user.

4) The rules differ in color probably due to differing aging effects ofrom light exposure

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