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Unit 1-Electrical Energy EET 110 Electronics Survey I Topics to Cover • Fundamentals of: – Current – Circuits – Loads – Measuring Electricity Current • Electrons, Protons, and Neutrons • Law of Charges • Induction Matter ELEMENTS: Pure forms of matter ATOMS: Smallest part of an element COMPOUNDS: Mixtures of two or more elements MOLECULE: Smallest part of a compound Electrons: Negative part of atom Protons: Positive part of atom Neutrons: No charge or neutral part of atom Atomic Structure Electron • Electrons are held to • • nucleus by attraction The number of protons and electrons are generally equal Atoms are arranged on the periodic table by the number of protons and electrons (atomic number) Proton Neutron Ionization • Energy added to atom causes excitement • Electrons leave orbital rings causing electrical unbalance – Atoms which loose electrons have more protons and therefore are positive – Atoms which gain electrons have more electrons and therefore are negative Ionized atoms Electron Proton Neutron Neutron Polarity Marking • Indicate importance of + or – • No marking means either direction will work Law of Charges • Conventional Flow Theory – 200 years ago – Arbitrarily decided current flowed from + > - • Electron Flow Theory – Discovery of atom and semiconductor proved conventional theory incorrect – ELECTRONS FLOW from NEGATIVE to POSITIVE IMPORTANT POINT • Correct polarity must be maintained when building circuits with devices that require a definite polarity! Circuits • Complete Pathway on which a current flows – Source – Conductor – Load Loads • Resistance connected across a circuit that determines current flow and energy used – Lights – Electrical appliances – Resister Measuring Electricity • Meters come in two formats – Analog Meters – Digital Meters • Voltmeter • Ammeter • Ohmmeter Analog Meter Digital Meter Voltmeter • Measures Voltage – Force Behind Electron Flow (E) • Connected in Parallel • Circuit must be energized Ammeter • Measures Current flow in Amperage (I) – The amount of electrons flowing past a given point in one second is the amperage • Connected in Series • Circuit must be energized Ohmmeter • Measures Resistance in Ohms (R) – The opposition to electrical flow • Connected in Parallel • Circuit must BE NOT CONNECTED to source