Photometry

PIRA classification 6B

Grayed Demos are either not available or haven't been built yet.

6B10. Luminosity

PIRA #

Demonstration Name

Abstract

6B10.10

checker board

Use a point source to superimpose shadows of a rectangle and a 3h x 3w checkerboard rectangle.

6B10.10

inverse square law

A rectangular paddle and a 3Hx3W paddle are placed so shadows overlap and the distances are measured.

6B10.15

inverse square model

A wire frame pyramid connects areas of 1, 4, and 16 units.

6B10.15

inverse square model

A wire frame pyramid connects areas of 1, 4, and 16 units.

6B10.20

inverse square with photocell

Double and triple the distance from an arc source to a photocell connected to a galvanometer.

6B10.20

foot-candle meter

Use a Weston type foot-candle meter to measure the inverse square law.

6B10.20

inverse square law

Double and triple the distance between a source and photometer. Graph.

6B10.30

paraffin block photometer

Two large paraffin blocks with tin foil sandwiched in between make a sensitive photometer. Use with lamps on either side.

6B10.30

paraffin blick photometer

Two paraffin blocks separated by an aluminum sheet are moved between two light sources until they appear equally bright.

6B10.30

Joly diffusion photometer

Tin foil is sandwiched between two blocks of paraffin. Can be mounted in a box for greater accuracy.

6B10.35

grease spot photometer

A piece of paper with a grease spot is moved between two light sources until the spot disappears.

6B10.35

Bunsen grease-spot photometer

A grease spot disappears when illuminated equally from both sides. Diagram of a grease-spot box.

6B10.40

Rumford photometer

Light sources are moved until their shadows of the same object are of equal intensity.

6B10.40

Rumford shadow photometer

Two light sources are moved so the shadow cast by a vertical rod is of the same intensity.

6B10.50

frosted globe - surface brightness

The surface brightness of a 40 W bulb is compared to a frosted globe placed over it.

6B10.50

surface brightness

A lamp with measured candlepower is enclosed in a frosted globe.

6B10.60

surface brightness of a lens

Place the eye at the image point of a lens focused on a dim lamp.

6B10.65

reflected surface brightness

With a bright spot at the object point of a concave mirror and the eye at the image point, the whole mirror seems to have the same surface brightness as the spot.

6B10.70

laser and light bulb

A .5 mW laser beam can be seen on the glass beside the bright center of a 25 W frosted incandescent bulb.

6B10.80

covered strobe and detector

The amplitude of a signal displayed on an oscilloscope from a translucent covered photodetector and from a translucent covered strobe changes as the angles and distances are changed.

6B30. Radiation Pressure

PIRA #

Demonstration Name

Abstract

6B30.10

radiometer - quartz fiber

6B30.10

radiation pressure

Construction details for a quartz fiber radiometer. Deflection of one radian is easily achieved with a microscope lamp.

6B30.10

radiometer

The deflection of a quartz fiber radiometer is measured statically under high vacuum.

6B30.11

radiometer

Focus a beam of light intermittently on a vane of the quartz fiber radiometer at the frequency of oscillation.

6B30.20

light pressure comment

Brings attention to a paper that devotes six pages to describing errors in the "classical work by Nichols and Hull".

6B40. Black Bodies

PIRA #

Demonstration Name

Abstract

6B40.10

variac and light bulb

Vary the voltage to a 1 KW light bulb with a variac to show color change with temperature.

6B40.10

variac and light bulb

Vary the voltage across a clear glass lamp from zero to 50% overvoltage. Also measure the intensity and plot against power.

6B40.20

hole in a box

Holes in black boxes are blacker than the boxes. One box is painted white inside.

6B40.20

hole in a black box

A box painted black has a hole in the side.

6B40.20

Bichsel boxes

Two black boxes have blacker appearing holes in them. One box actually is painted white inside.

6B40.25

carbon block

A carbon block with a hole bored in it is heated red hot with a torch. The hole glows brighter.

6B40.25

hole in a hot ball

A iron ball with a hole is heated red hot.

6B40.26

carbon rod

Bore a hole in an old carbon arc rod and heat electrically. The hole glows brighter.

6B40.30

radiation from a black body

Heat red hot a carbon block the has both a drilled hole and a white porcelain plug.

6B40.30

carbon block and porcelain

Two holes are drilled in a carbon block, one is filled with a porcelain insulator, and the block is heated with a torch.

6B40.30

graphite and porcelain

Graphite and porcelain heated red hot look the same. A pattern on a porcelain dish shows brighter when heated.

6B40.35

good absorbers - good radiators

An electric element (E-171) with chalk marks or china with a pattern are heated until they glow.

6B40.40

X-Y spectrum recorder

The black body radiation curve is traced on a X-Y recorder from a thermopile. detector riding on the pen arm.

6B40.41

IR spectrum on galvanometer

6B40.41

plotting the spectrum

Measure the output of a thermopile. as it is moved across a spectrum. Monochrometer in appendix, p. 1362, Plots.

6B40.41

radiation intensity curve

Explore the energy distribution of the continuous spectrum of a carbon arc with a sensitive thermopile. and galvanometer.

6B40.41

infrared in spectrum

Hold a thermopile. connected to a galvanometer in different parts of a spectrum.

6B40.42

mapping the spectrum

Use a thermopile. and galvanometer to show the infrared energy in the continuous spectrum. Insert a water cell.

6B40.45

IR camera and projected spectrum

6B40.50

IR camera and soldering iron

6B40.55

project sprectrum and change temperature

6B40.55

radiation vs. temperature

A more detailed look at varying the temperature of a black body and measuring with a thermopile.

6B40.55

radiation spectrum of a hot object

Project the spectrum from a projector lamp and change the voltage.

6B40.62

Stefan-Boltzman equation

Measuring sigma by the relative method using a Hefner lamp as a standard radiator.

6B40.70

microwave blackbody

Microwave radiation emitted or absorbed by a cavity is detected and displayed on an oscilloscope.

Demonstrations

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