How Things really Work The Physics behind

Everyday LifeThur July 7: Afternoon  Session 2:  12:30 – 3 PM . Fiber Optics and Energy Transformations

Learning Objectives: •Understand how fiber optic work•Understand the applications of fiber optics •Understand the principles behind energy transformation in terms of solar and wind energy

Fiber Optics• An optical fiber (or fibre) is a glass or plastic fiber that carries light along its length. Fiber optics is

the overlap of applied science and engineering concerned with the design and application of optical fibers. Optical fibers are widely used in fiber-optic communications, which permits transmission over longer distances and at higher bandwidths (data rates) than other forms of communications. Fibers are used instead of metal wires because signals travel along them with less loss, and they are also immune to electromagnetic interference. Fibers are also used for illumination, and are wrapped in bundles so they can be used to carry images, thus allowing viewing in tight spaces. Specially designed fibers are used for a variety of other applications, including sensors and fiber lasers.

• Light is kept in the core of the optical fiber by total internal reflection. This causes the fiber to act as a waveguide. Fibers which support many propagation paths or transverse modes are called multi-mode fibers (MMF), while those which can only support a single mode are called single-mode fibers (SMF). Multi-mode fibers generally have a larger core diameter, and are used for short-distance communication links and for applications where high power must be transmitted. Single-mode fibers are used for most communication links longer than 550 meters (600 yards).

• Joining lengths of optical fiber is more complex than joining electrical wire or cable. The ends of the fibers must be carefully cleaved, and then spliced together either mechanically or by fusing them together with an electric arc. Special connectors are used to make removable connections.

Lab 1 Fiber Optical Tree • Procedure: View the fiber optical tree" and describe

in your worksheet what you think is happening.

http://demo.physics.uiuc.edu/LectDemo/scripts/demo_descript.idc?DemoID=290

Lab 2 Optical water fiber - the Tyndall's experiment

• Procedure: http://www.lightwave.soton.ac.uk/experiments/waterfibre/waterfibre.html

• View the demonstrations describe what you think is happening.

http://www.youtube.com/watch?v=L9cBKEY54oE

Lab 3 Bending Light• http://demo.physics.uiuc.edu/LectDemo/scripts/demo_descript.idc?DemoID=429

• View the demonstrations describe in your worksheet what you think is happening.

http://www.eas.asu.edu/~palais/490s00/Radiation.htm

http://www.eas.asu.edu/~palais/490s00/Radiation.htm

Light Photons

Lab 4 - Fiber Optics Applications:

• Telecommunications: Optical fiber can be used as a medium for telecommunication and networking because it is flexible and can be bundled as cables. It is especially advantageous for long-distance communications, because light propagates through the fiber with little attenuation compared to electrical cables. This allows long distances to be spanned with few repeaters.

• Fiber optic sensors: Fibers have many uses in remote sensing. In some applications, the sensor is itself an optical fiber. In other cases, fiber is used to connect a non-fiberoptic sensor to a measurement system. Depending on the application, fiber may be used because of its small size, or the fact that no electrical power is needed at the remote location, or because many sensors can be multiplexed along the length of a fiber by using different wavelengths of light for each sensor, or by sensing the time delay as light passes along the fiber through each sensor. Time delay can be determined using a device such as an optical time-domain reflectometer.

• Other uses of optical fibers: Fibers are widely used in illumination applications. They are used as light guides in medical and other applications where bright light needs to be shone on a target without a clear line-of-sight path. In some buildings, optical fibers are used to route sunlight from the roof to other parts of the building (see non-imaging optics). Optical fiber illumination is also used for decorative applications, including signs, art, and artificial Christmas trees.

A TOSLINK fiber optic audio A bundle of optical fibers

Fiber Optic Computer Cables Fiber Optic Switch

Entertainment Systems Communication Systems

Solar Photovoltaics -

Solar Light to Electric

Lab 5 Energy Transformations• Solar Photovoltaics - Solar Light to Electric

– The term photovoltaic means it uses a photodiode device. A photodiode is a type of photodetector capable of converting light into either electrical current or voltage, depending upon the mode of operation.

• Solar Thermal - Solar Light to Heat– Solar thermal energy (STE) is a technology for harnessing solar

radiation energy for thermal energy (heat). – Solar thermal collectors are defined as low-, medium-, or high-

temperature collectors.• Low temperature collectors are flat plates generally used to heat

swimming pools. • Medium-temperature collectors are also usually flat plates but are used

for creating hot water for residential and commercial use. High temperature collectors concentrate sunlight using mirrors or lenses and are generally used for electric power production.

– STE is different from photovoltaics, which convert solar energy directly into electricity.

Solar ThermalSolar Light to Heat

Flat Plate Collector

Wind Power 

 

Commercialhttp://www.youtube.com/watch?v=Gu3EyzOYpGY&NR=1

http://www.youtube.com/watch?v=IZI9manAyDE&feature=related

Home madehttp://www.youtube.com/watch?v=MZhHCyuEEDk

http://www.youtube.com/watch?v=QkoJMt-B-U4&feature=relatedhttp://www.youtube.com/watch?v=e2zCq_Si0SI

Wind turbine explodes http://www.youtube.com/watch?v=u14tBwO5QVQ

http://www.youtube.com/watch?v=lvvRHhsQhi8&NR=1