Basic Electronics - Back to Basic Back Electricity Atomic...

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Unformatted text preview: Back to Basic Back Electricity Atomic Structure Atomic Electricity is an essential ingredient of matter! The Atom ­ Protons ­ Neutrons ­ Electrons Atomic Structure Atomic The Structure of the atom is similar to our solar system - Planets are held in orbit by gravity - Electrons are held in orbit by their attraction to the nucleus Ions Ions Have equal amount of electrons and protons Charges cancel each other out No electrical charge Positive Ions Positive One or more electrons are dislodged from and atom The atom now has a positive net charge Creating a Positive Ion Negative Ion Negative A stray electron combines with a normal atom The atom now has a net negative charge Creating a Negative Ion The Electron The Negatively charged part of an atom Free electrons can move at high speeds through metals, gases, and vacuums The Electron The ­ Many trillions of electrons can rest on a surface or travel through space or matter at the speed of light! (That’s 186,000 miles per second WHOA!!!) Resting v. Moving Electrons Resting Resting Electrons: Groups of electrons on a surface create a (–) charged surface. This is said to be: NEGATIVE STATIC ELECTRICAL CHARGE Resting v. Moving Electrons Resting Moving Electrons: A stream of moving electrons is called: ELECTRICAL CURRENT Resting Electrons can quickly turn into electrical current if placed near a cluster of positive ions. Electric Current Electric The quantity of electrons passing a giving point The unit of current is Ampere (A) 1 Ampere is 6,250,000,000,000,000,000 (6.25x1018) electrons passing a point in one second Electric Current Electric Electric current is the motion of electric charges from one point to another. A voltage or pressure applied to a material causes electrons to be removed from an atom. Electric Pressure (Voltage) Electric Voltage is electrical pressure or force Voltage is often referred to as Potential Difference Voltage Drop: the difference in voltage between the 2 ends of the conductor through which the current is flowing Electrical Resistance Electrical Resistance is the opposition to the flow of current Resistance is measured in Ohms (Ω) Conductors Conductors A material through which current flows is called conductor. Conductors have low resistance to electric current flow and allow electrons to move easily. Insulators Insulators Some materials have a high resistance to the movement of electric current. The electrons in outer orbits of these insulators are more than half­filled with electrons and are difficult to release. Insulators include plastic, glass, and rubber . Semiconductors Semiconductors Materials called semiconductors have become very important in electronics. Semiconductor materials are not conductors and not insulators. They do not conduct electric current easily and are not good insulators. Electronic Circuits A circuit is a path or conductor for A circuit is a path or conductor for electric current flow. 3 types of circuits: Closed circuit Open circuit Short circuit? Closed Circuit Closed Closed circuit means an electric current flows only when it has a complete path. There must be a source of electric energy to cause current to flow along a closed path. Open Circuit Open Electric current cannot flow if a circuit is open. An open circuit does not provide a complete path for current flow. An example of an open circuit occurs when a switch is used. Every time you flip a switch off you create an open circuit Short Circuit Short . A short circuit occurs when a conductor connects directly across the terminals of an electric energy source. If a wire is placed across a battery, a short circuit occurs. Short circuits cause too much current to flow from the source Current Flow in Circuits Current Electron and conventional current flow should not be confusing. They are two different ways of looking at current flow. Electron Flow Conventional Flow ­ + + ­ Essentials for any circuit Essentials You must have 3 essential key parts to make a circuit ­Potential Difference (voltage) ­Conductors (wires) ­Load (motor, light bulb, fan) ...
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This note was uploaded on 10/23/2011 for the course DESHIGN AN 1910265 taught by Professor Lewis during the Spring '11 term at Thomas Jefferson School of Law.

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