Physics Test #3 Flashcards
Charge
a fundamental property of matter…imbalance of protons and electrons
SI unit of charge
coulomb
Conductors
transmit charges readily
Semiconductors
intermediate; their conductivity depends on impurities and can be manipulated by external voltages
Insulators
do not transmit charge easily
Induction
the process of generating a current in a conductor by placing it in a changing magnetic field
Coulomb’s Law
two charged objects feel a force between them
Superposition Principle
the net effect of all charges in an arrangement is the same as the sum of the individual effects of each charge taken seperately
Electric Field
a region around a charged particle within which a force would be exerted on other charged particles (vector)
Uniform Electric Field
have same direction and magnitude
Work
the transfer of energy to or from a system
Electric Potential
the amount of work needed to move a charge from a reference point to a specific point against an electric field (a scalar)
Potential Energy (per unit charge)
a measure of how much each charge effects the total energy
Electric Potential Units
J/C (volt)
Potential Difference
delta V
Equipotential Lines
connect points of the same potential; always perpendicular to electric field lines
Capacitance
the ratio of charge to potential difference (farad or 1 C/V)
Parallel Plate Capacitor
any two charged objects form a capacitor; between plates electric field is constant
Battery
used to move charge (Q) and charge the capacitor
Dielectrics
nonconducting material between the plates of a capacitor used to increase capacitance; ratio of the capacitance with and without (k)
Electric Current
the net change in charge per unit time (A)
Conventional Current
assumes charges are positive
Resistance depends on
size and shape of material; and type of material
Resistivity (P-rho)
a property of a material type (amount)
Resistance (R)
a particular element (size)…flow of charge is effected by the material it travels through
Resistance SI Unit
ohm
Resistors in Series
add resistors together
Resistors in Parallel
add reciprocals
Capacitors in Series
add reciprocals
Capacitors in Parallel
add capacitors together
Power
the rate at which work is done
SI units of Power
Watts (J/s)
Voltmeter
measures voltage across a component; hooked up in parallel
Ammeter
measures current through a component; hooked up in series
Junction Rule
total current entering a junction must equal the total current exiting a junction
Junction
the point where three or more wires intersect
Loop Rule
sum of potential differences around any closed loop is 0
Loop
any complete closed path around a circuit
Travel direction from - to +
+E
Travel direction from + to -
-E
Travel direction opposite to current direction
+IR
Travel direction in current direction
-IR
Nano-coulomb (nC)
10^-9
Micro-coulomb (uC)
10^-6
Milli-coulomb (mC)
10^-3
