ELET Ch1 Flashcards
Anything that has weight and occupies space.
Matter
Charge is measured in _______
Coulombs (C)
A substance that can’t be broken down into simpler substances
Element
Smallest particle of matter that retains the physical characteristics of an element
Atom
The simplest model of an atom.
The central core (nucleus) contains protons & neutrons.
Electrons revolve around the nucleus.
Bohr Model
Number of protons
Atomic number
Outtermost shell of an atom.
Valence shell
Force that causes two particles to be attracted to or repel from each other
Charge
An atom with a positive net charge
Positive ion
An atom with a negative net charge
Negative ion
An electron that isn’t bound to any particular atom.
It can neutralize a positive ion.
Free electron
The directed flow of charge through a conductor.
Current
Measurement for current
Charge per unit time
I=Q/t
True or False
Thermal energy (heat) is sufficient to free electrons in copper.
True
True or False
Free electron motion is random unless outside force is applied
True
I is the symbol for _____ and stands for ________.
Current.
Intensity.
Q is the symbol for _______ and is measured in _________
Charge
Coulombs
Represents the total charge of approximately 6.25x10^18 electrons
Coulomb (C)
Unit of current and is equal to
1C/s or 1 Coulomb per second
1A Amphere
Current that is unidirectional is known as _______
Direct Current (DC)
Current that is bidirectional is known as _______
Alternating Current (AC)
A difference in potential that generates a directed flow of a charge or current.
Voltage
The unit of measurement for voltage.
It is the difference of potential energy that uses one joule of energy to move one Coulomb of charge.
1J/C=
Volt
A measure of the ease which current will pass through a component.
Conductance (G)
G=1/R
R=Resistance
Conductance is most commonly measured in _______
Siemens (S)
Materials that provide little opposition to the flow of current.
Have few valence shell electrons
Conductors
Materials that normally block current.
Normally have a complete valence shell.
Insulators
Materials like graphite, silicone, or germanium that are neither good condurctors nor good insulators.
Half complete valence shells
Semiconductors
The resistance of a specified volume of an element or compound
Resistivity
R= (resistivity) x (length/cross sectional area)
