Transcript Unit 1-Electrical Energy

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
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