Colin Donnelly-
Current
Current is the movement of charge that occurs between two points that have different electrical potentials.
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By convention, current is defined as the movement of _____ from the _____ of a voltage source to the _____.
positive charge
high-potential end -> low-potential end
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In reality, it is _____ that move in a circuit, from _____ to _____.
negatively charged particles (electrons)
low potential -> high potential
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Current flows only in _____.
conductive materials
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Metallic conduction
Metallic conduction relies on uniform movement of free electrons in metallic bonds.
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Electrolytic conduction
Electrolytic conduction relies on the ion concentration of a solution.
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Insulators
Insulators are materials that do not conduct a current.
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Kirchhoff’s laws express conservation of _____ and _____.
charge and energy
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Kirchhoff’s junction rule
Kirchhoff’s junction rule states that the sum of currents directed into a point within a circuit equals the sum of the currents directed away from that point.
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Kirchhoff’s loop rule
Kirchhoff’s loop rule states that in a closed loop, the sum of voltage sources is always equal to the sum of voltage drops.
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Resistance
Resistance is opposition to the movement of electrons through a material.
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Resistors
Resistors are conductive materials with a moderate amount of resistance that slow down electrons without stopping them.
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Resistance is calculated using the _____, _____, and _____ of the material in question.
resistivity, length, and cross-sectional area
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Ohm’s law
Ohm’s law states that for a given resistance, the magnitude of the current through a resistor is proportional to the voltage drop across the resistor.
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Resistors in series
Resistors in series are additive and sum together to create the total resistance of a circuit.
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Resistors in parallel
Resistors in parallel cause a decrease in equivalent resistance of a circuit.
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Across each resistor in a circuit, a certain amount of power is dissipated, which is dependent on the _____ and the _____.
current through the resistor
voltage drop across the resistor
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Capacitors have the ability to _____ and _____ electrical potential energy.
store and discharge
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Capacitance in parallel plate capacitors is determined by the _____ and the _____.
area of the plates
distance between the plates
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Capacitors in series cause a _____ in the equivalent capacitance of a circuit.
decrease
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Capacitors in parallel _____ to create a _____ equivalent capacitance.
sum together
larger
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Dielectric materials
Dielectric materials are insulators placed between the plates of a capacitor that increase capacitance by a factor equal to the material’s dielectric constant, κ.
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Ammeters
Ammeters are inserted in series in a circuit to measure current; they have negligible resistance.
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Voltmeters
Voltmeters are inserted in parallel in a circuit to measure a voltage drop; they have very large resistances.
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Ohmmeters
Ohmmeters are inserted around a resistive element to measure resistance; they are self-powered and have negligible resistance.
