University:
Eastern Kentucky University
Course:
PHY 132 | College Physics II
Academic year:

2020
Views:

370

Pages:

1
Author:

Jameson Hunt

Physics and Math 6: Circuits Charges Capacitance and Capacitors Current: The movement of charge that occurs between two points that have different electrical potentials. By convention, current is defined as the mvmt of positive charge from the highpotential end of a voltage source to the low-potential end. In reality, it is negatively-charged particles (electrons) that move in a circuit, from low potential to high potential $ 𝐼 =# ∆& Conductive Metallic Conduction: The flow of current due to movement of Materials: electrons Electrolytic Conduction: The movement of free ions under electric field Insulators: Materials that do not conduct a current Kirchhoff’s Express conservation of charge and energy. Laws: Junction Rule: The sum of the currents flowing into a junction is equal to the sum of the currents flowing out of that junction. 𝐼'()*#+,-.&/0- =𝐼1234'(5#67(8)'*( Loop Rule: In a closed loop, the sum of voltage sources is always equal to the sum of voltage drops. 𝑉:*7;82=𝑉 <;*= Resistance Resistance: Resistors: The opposition that a substance offers to the flow of e-. Conductive materials with a moderate amount of resistance that slow down electrons without stopping them. r#? 𝑅 =# @ r = resistivity , 𝐿=length#of#resistor , 𝐴=cross#sectional#area Capacitors: Have the ability to store and discharge electrical potential energy. Capacitance: In parallel plate capacitors, it is determined by the area of the plates and the distance between the plates. $ 𝐶 =# S Capacitance based on parallel plate geometry: Electric field in a capacitor: 𝐸 =# V Z Series / Parallel: Dielectric Materials: Series: ¯equivalent capacitance of a circuit Parallel: Sum together to create a large equivalent capacitance Insulators placed between the plates of a capacitor that increase capacitance by a factor equal to the material’s dielectric constant, k Meters Ammeters: Inserted in SERIES in a circuit to measure current; they have negligible resistance Voltmeters: Inserted in PARALLEL in a circuit to measure a voltage drop; they have very large resistances Ohmmeters: Inserted around a resistive element to measure resistance; they are self-powered and have negligible resistance Resistors in Series: Additive. Sum together to create the total resistance of a circuit. Resistors in Parallel: ¯equivalent resistance of a circuit. Capacitors in Series: The total capacitance of capacitors in series is equal to the reciprocal of the sum of the reciprocals of their individual capacitances. Total capacitance will always be less than the value of the smallest capacitor. Z Z Z Z Z =# #+# +# + ⋯ +# fg Resistors in Parallel: To get the total resistance, add the reciprocals of the resistances of each component and take the reciprocal of the sum. Total resistance will always be less than the value of the smallest resistance. Z Z Z Z Z =# #+# +# + ⋯ +# `a `b `c `d `e V Potential energy of a capacitor: 𝑈 =# [ #𝐶#𝑉[ Ohm’s Law: For a given resistance, the magnitude of the current through a resistor is proportional to the voltage drop across the resistor. 𝑉 =𝐼#𝑅 Resistors in Series: Total resistance is equal to the sum of all the individual resistors. 𝑅: =𝑅Z +𝑅[ +𝑅^ +⋯ +𝑅- @ 𝐶 =# eT #( ) S fb fc fd fe Capacitors in Parallel: Total capacitance is equal to the sum of all the individual capacitances. 𝐶= =𝐶Z +𝐶[ +𝐶^ +⋯ +𝐶-

Physics and Math 6 Circuits

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