The Electromagnetic Spectrum Outcomes: http://www.avclub.com/article/marvel-made-its-own-movies-ang-lee-offered-idiosyn-204118 Qualitatively describe the electromagnetic spectrum in terms of frequency, wavelength, and energy. Recognize, through direct observation, that elements have unique line spectra Include: flame tests or gas discharge tubes, spectroscopes or diffraction gratings) Describe applications and/or natural occurrences of line spectra. Examples: astronomy, aurora borealis, fireworks, neon lights.
Electromagnetic Radiation Is a form of ENERGY that exhibits WAVE-LIKE behaviours as it travels through space. VISIBLE LIGHT is a type of electromagnetic radiation. Other examples are X-RAYS, MICROWAVES, U.V. LIGHT, etc. Consists of OSCILLATING ELECTRIC and MAGNETIC FIELDS that are PERPENDICULAR to each other: https://micro.magnet.fsu.edu/primer/java/electromagnetic/
Waves Can be described in terms of their WAVELENGTH, AMPLITUDE, FREQUENCY, and ENERGY. 1. Wavelength (λ): Is the DISTANCE between two successive CRESTS (or TROUGHS) of a wave. It is the distance a wave travels as it completes a full UPWARD and DOWNWARD CYCLE. VISIBLE LIGHT (EM Radiation that you can see) has wavelengths between 400-750 nm (10-9 m = 1nm). http://www.studyphysics.ca/newnotes/20/unit03_mechanicalwaves/chp141516_waves/lesson44.htm
Waves 2. Amplitude (A): The HEIGHT of the wave measured from its ORIGIN to its CREST. http://cimss.ssec.wisc.edu/satmet.2012-feb-14/modules/spectrum/wavelength.html
Waves 3. Frequency (ν): Tells us how FAST the wave OSCILLATES up and down. Frequency is measured by how many times a wave can complete a CYCLE of up and down motion in ONE SECOND. Units are CYCLES PER SECOND or 1/s. This is also called a HERTZ (Hz) (like in your computer processors) Notice that the HIGHER the FREQUENCY, the SHORTER the WAVELENGTH. http://www.sciencebuddies.org/science-fair-projects/project_ideas/music_p010.shtml
Waves 4. Energy (E) The HIGHER the FREQUENCY of a wave, the HIGHER the ENERGY. http://geoinfo.amu.edu.pl/wpk/rst/rst/intro/part2_2.html All electromagnetic waves travel at the same SPEED, the SPEED OF LIGHT (c = 3.0x108 m/s), but they vary in their wavelengths, frequencies, and energies.
The Electromagnetic Spectrum If sunlight passes through a PRISM, the light gets spread into a rainbow of COLOURS (like in rainbows, & on CD s). http://www.tutorvista.com/physics/dispersion-of-white-light This is called the VISIBLE SPECTRUM of light, and is CONTINUOUS because each colour blends into the next.
The Electromagnetic Spectrum The different colours have different WAVELENGTHS, and therefore different FREQUENCIES and ENERGIES. (red is lowest, and violet is highest) https://www.behance.net/gallery/7485617/dark-side-of-the-moon The visible light order can be remembered by Roy G. Biv. (red, orange, yellow, green, blue, indigo, violet)
The Electromagnetic Spectrum VISIBLE LIGHT is a small part of the Electromagnetic Spectrum, the rest we CANNOT SEE (u.v., x-rays, etc)
The Electromagnetic Spectrum
The Electromagnetic Spectrum Line Spectra When an ELECTRIC CURRENT passed through hydrogen gas in a tube the gas glows. If the light produced is focused through a slit is passed through a prism, a SPECTRUM with DISTINCT LINES is produced. http://chemistry.tutorvista.com/inorganic-chemistry/spectral-lines.html
The Electromagnetic Spectrum This type of spectrum is known as an EMISSION SPECTRUM, since it is the separate WAVELENGTHS of light emitted by the GAS. http://sciexplorer.blogspot.ca/2014/02/history-of-periodic-table-part-3.html This emission spectrum is also known as a LINE SPECTRUM because the light separates into discrete WAVELENGTHS of light that appear as lines of colour on a screen or photographic plate. Unlike a CONTINUOUS spectrum, the colours in a LINE spectrum DO NOT BLEND into each other.
Hydrogen s Line Spectrum The visible region of the emission spectrum of hydrogen is shown in the figure below. https://www.quora.com/who-developed-orbital-shells-and-why Each coloured line corresponds to an exact WAVELENGTH or FREQUENCY of light. Emission Spectrum Simulation
Spectroscopy (Spectrophotometry) Are names given to the TECHNIQUES used to determine a substance s EMISSION SPECTRUM Below are the EMISSION or LINE SPECTRA of several other elements. https://socratic.org/questions/how-does-the-bohr-theory-of-the-atom-explain-flame-colors If you examine these spectra you will notice they are all DIFFERENT. The line spectrum of each element is like the FINGERPRINT of that element.
Spectroscopy (Spectrophotometry) Below are the EMISSION or LINE SPECTRA of elements we have available at out school:
Flame Tests In 1870 the bright yellow line in helium s spectrum was first seen when examining the light emitted by the Sun. The discoverers determined this was a new element and named the element helium, after the Greek Sun god helios. Twenty five years later helium was discovered on Earth. Flame Tests: When some elements are BURNED, they emit a DISTINCTIVE COLOUR of light. This is due to the emission of light predominantly in that wavelength in their LINE SPECTRUM. The PRESENCE of a metal is can be detected by the colour that results when it is placed in a flame. This is known as a FLAME TEST.
Flame Tests SALTS containing the metals, when placed into a flame will give the flame the colours as shown below: Colour green yellow red yellow-green orange-red purple purple-red Element copper sodium strontium barium calcium potassium lithium https://socratic.org/questions/why-are-chlorides-used-in-flame-test Some commercially made fireplace logs advertise that they will produce multi-coloured flames, when burned. This is because the logs are made of pressed sawdust or smaller chips of wood soaked in a solution containing several metal salts. You can also see colourful flames if you burn the paper from newspapers or magazines with colour pictures, since the coloured inks contain various metal salts.
Applications of Line Spectra Astronomers use line spectra to DETERMINE the ELEMENTS in various light sources, such as STARS and NEBULAE. The AURORA BOREALIS (northern lights) result from IONIZED GASES becoming excited which leads to the release of LIGHT which you can see in the northern sky. METAL SALTS are used in FIREWORKS to produce the distinctive colours of light. Below is an example of a fireworks shell that contains copper and strontium for a burst that will have both red and green. http://www.dlt.ncssm.edu/tiger/diagrams/structure/fireworks_crosssection640.gif