Overview
- This is a combined unit of two components: Electrostatic & Circuit
- Electro-static
- We discovered that electric charge is a conserved quantity and is discrete in nature. We identifies how charging char or separation distance will impact electric force. We learned how to describe the process of charging by conduction or induction and how to differentiate between a net neutral object with an induced charge v.s an object with a net charge, as well as applying conservation of charge in charging processes.
- Circuit
- in this section we explored the concepts of current, voltage, resistance, and power of a circuit, and also the relationship between them. We explored different ways to connect a circuit (in series and in parallel).
- Electro-static
Charge and Electric Force
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https://cnx.org/contents/[email protected]:6i7bos_V/Conductors-Insulators-and-Charging-by-Induction
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Helpful Video on Electrostatics!!!
Circuits
Key Terms
Equations
- Current (I) - measure of how much charge passes through a given area over time; SI units of Ampere (A).
- Ampere (A) - current equivalent to 1 coulomb of charge per second
- Direct Current (DC) - constant flow of charge in one direction
- Battery - device that transforms chemical energy into electrical energy; an ideal battery has no internal resistance
- Resistance (R) - measure of how much an object resists current flow; depends on resistivity of the material, length, and cross sectional area; SI units of Ohms (Ω)
- Resistors - devices used to reduce current flow
- Resistivity (ρ) - measure of how much a specific material resists current flow; SI units of Ω⋅m
- Ohm (Ω) - the unit of electrical resistance
- Voltage (V) - also known as electric potential difference; energy change per unit charge between two points; SI units of Volts (V)
Equations
- Least resistance - large cross-sectional area, short length, small resistivity
- most resistance - small cross-sectional area, long length, high resistivity
- Energy is conserved in a circuit. As electrons flow through a circuit, they lose electrical potential energy, and when they get back o the battery, the battery gives electrical potential energy to electrons as they flow. The battery gives them the exact amount of energy they "lost" through the whole circuit.
Ohm's Law
- Ohm’s law states that for some devices there is a relationship between electric potential difference, current, and resistance
- Equation (figure on the left)
- For a given resistance (R), increasing the electric potential difference (ΔV) increases the current (I) and vice versa
- For a given electric potential difference (ΔV), if the resistance (R) increases, then the current (I) decreases and vice versa
- For a given current (I), if the electric potential difference (ΔV) increases, then the resistance (R) also increases and vice versa
Kirchhoff's Rules
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Helpful Video on Electricity!!! (good summary of the unit)
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