Film: 5753

Science | 1950 | Sound | Colour

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Synopsis:

Two boys operate a school spectrometer 1950's

Close up reveals the collimator, prisms and telescope. Close up of a copper spectrum displayed on a screen. A boy replaces the spectrometer’s eye piece by a camera, thus turning the spectrometer into a spectrograph. A student examines a spectrograph. A diagram illustrates how a spectrograph works: light from a source passes through a slit to a collimating lens to produce a parallel beam, on refraction through the prism, the light breaks up into its various wavelengths, the wavelengths are then focused on the photographic plate, the larger the prism, the larger the resolving power. Close up to show the arrangement of lenses and prisms in a medium size spectrograph. Pan of the spectrograph sitting on a laboratory bench, above it are two shelves with chemical bottles. A man set up the glass spectrograph. Close up of a copper spectrograph. A diagram explains the glass optical system and the quartz optical system. Comparison of the spectra obtained using a glass optical system and a quartz optical system. A spectrum obtained using a quartz system is used to illustrate the photographic range. Close up of a man operating the spectrograph. Close up to show the diaphragm which slides across the slit, this enables three spectra to be compared simultaneously.

A spectrogram that resulted from three overlapping spectra. A spectrograph of sample A compared to the spectrograph of iron. Close up of a diffraction gradient which can be used instead of a prism. Close up of the diffraction gradient glass mirror (wonderful spectrum rainbow colours). A spectrograph produced by a diffraction gradient. A quartz spectrograph (line spectrum). An animation describes what causes line spectra (electrons revolving in orbit around the atoms nucleus; each orbit has its own energy shell and are numbered K,L,M,N,O,P; electrons leap from one stationary state to another, the orbit close to the nucleus is called ground state; for an electron to jump from one state to another it must give off a quantum of energy, when the electron goes back to the lower energy level it gives off the same spark of energy it received, that is, it emits a photon (monochromatic light). The colours of the different frequencies mingle together, thus become the characteristic light of the element when excited. Spectrograph of hydrogen (pinkish glow), spectrograph of sodium (yellow), spectrograph of copper (green)followed by spectrographs of various elements. A nitrogen band spectrum. Close up of a vacuum tube where a molecule (nitrogen) is being excited. View of a man observing the vacuum tube connected to the spectrograph. A high resolution band spectra. An animation describes the three types of energy present in a molecule (rotation of its electrons, the vibration of the nuclei, rotation of the nuclei), it also describes what happens to the band spectrum when a quantum of energy is absorbed by the molecule. Close up of a continuos spectrum. Another view of the man observing the spectrograph.
Close up of a glowing lamp. The resulting spectra of a hot body such as a light bulb. Line, band and continuous spectra are classified as emission spectra. The man operating the spectrometer lights a sodium flame for analysis. Close up of the sodium flame. Close up a continuous spectrum produced by a white light passing through a sodium flame, a black band is visible, this indicates that the wavelength has been cancelled or absorbed. A diagram explains the previous spectra results. Comparison between continuous and emission spectra. The use of the spectrograph follows. Close up of an arc light (used for qualitative analysis). Close up of a sample of copper in a flask. A technician examines the copper sample for unwanted elements. The copper spectrograph is enlarged and projected, traces of impurities are pinpointed. Close up of sparks of light used in spectrographs for quantitative analysis. A microphotometer measures the density of spectrum lines. Close up of unknown spectrum lines being compared in density with known samples. A woman prepares samples for absorption spectroscopy. Close up of the cells, one with unknown sample and another with known sample, both samples are place in the absorption spectrometer. Close up of the graduated drum (selects wavelengths). Close up of the photocell. A technician analysis a sample for benzene. Close up of a trace which indicates the presence of benzene. A technician calculates the amount of benzene present in the sample. An infra red absorption spectrometer which is used in the petroleum industry. Close up of a trace produced by an infra red absorption spectrometer.

A foundry. A melt ( done in a foundry) is poured onto a mould for casting. The cast is taken to the lab for analysis. The cast is placed in the direct reading spectrograph. Close up of the recording trace. Pan of the direct reading spectrograph, a man watches the trace. The man records the results, close up of the results which give the go ahead at the foundry to melt the aluminium. Close up of melted aluminium. A man ploughs a field. A man collects soil samples from different layers in a field. A woman analysis the soil samples in a laboratory. Close up of the test tubes containing soil samples. Soil is analysed by the spectrometer. A man appears to be conducting a criminal investigation outside a house, he is examining a pole. Close up of the pole, this reveals a mechanic stain. A crowbar is examined to see it matches the stain found on the street pole. The resulting spectra. A statue of a Greek god is examined for authenticity. A man collects a sample from the statue which he places in the spectrograph for examination. The resulting spectra reveals that the statue is not more than 500 years old. Various shots of a solar spectrograph. A man wearing protective glasses prepares the spectrograph to examine solar )sun) light. The solar spectra reveals absorption lines. Solar spectra of the left and right edges of the sun. Close up of these spectra. A telescopic image of the stars.

( made in co-op with anglo Iranian Oil, Birbeck College, British museum, British non-ferrous metals research, Cambridge University Observatory, Hilger & Watts LTD, International Alloys LTD, Rothamstead Experimental Station.)


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