Ch20_IrwinA

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CHAPTER 20: ELECTRIC CIRCUITS PART 1

 * all schematic diagram lines should be straight
 * the lightbulbs in #6a should not be filled in, and they should all have lines around showing that they are lit.
 * __Investigation 23: Investigating the Air Capacitor__**
 * __Investigation 24: Practice Set - Capitance__**

CHAPTER 20: ELECTRIC CIRCUITS PART 2
Investigation 7 - Physics Classroom Summary

@http://www.physicsclassroom.com/Class/circuits/

Investigation 9 - Practice Set: Color Coding Investigation 10 - Practice Set: Color Coding Questions Investigation 14: Practice Set Battery Structure Investigation 16: Reading - Mixing Bulbs Investigation 20 - Practice Set: What Determines Pressure in Wires?

21- Lab: Ammeters and Voltmeters
Investigation 22 - True & False

**Lesson 1:**
** How do electric fields effect movement of charge? **Space is altered by the presence of a charged object. Charged objects create an electric field, exerting a force in the space around it. Electric fields are similar to gravitational fields. Charge will move from a high energy to low energy unless work is performed. Charge moves with the electric field. ** What is electric potential and what is its relationship with charge? **The amount of force involved doing the work required to move charge against an electric field is dependent upon the amount of charge being moved (according to Coulomb’s Law of electric forces). The greater the charge on the test charge, the greater the repulsive force and the more work that would have to be done on it to move it the same distance. Electric potential is a location-dependent quantity that expresses the amount of potential energy per unit of charge at a specified location. When a Coulomb of charge (or any given amount of charge) possesses a relatively large quantity of potential energy at a given location, then that location is said to be a location of high electric potential. And similarly, if a Coulomb of charge (or any given amount of charge) possesses a relatively small quantity of potential energy at a given location, then that location is said to be a location of low electric potential. ** What is electric potential difference? **Electric potential difference is the difference in electric potential between two different locations within an electric field.
 * Electric Potential Difference Summary**

**Lesson 2:**
**Electric Current Summary** ** What is an Electric Circuit? ** An electric circuit is a closed loop through which charge can continuously move. Current is the flow of charge through a circuit. Charge flows from areas of high electric potential to areas of low electric potential within a circuit. ** What are the requirements of a circuit? ** There must be a closed conducting path that extends from the positive terminal of the power supply to the negative terminal of the power supply. All connections must be made by conducting materials capable of carrying charge. There must be an energy supply. The difference in potential energy is what causes charge to flow. ** What is electric current? ** Current is the rate at which charge flows past a point on a circuit. I=Q/t, measured in Amps (A). The conventional direction of electric current is from positive to negative. Drift speed is the average distance traveled by a charge carrier per unit of time. This is very slow. ** What is power (in terms of circuits/electricity)? ** Power is the rate at which electrical energy is supplied to a circuit or consumed by a load. P=E/T (measured in Watt) ** What are some common misconceptions regarding electric circuits? ** Batteries are not rechargeable. The reasons batteries die there is no longer enough potential difference between terminals for charge to move. They cannot be recharged because they never lose charge.

**Lesson 3:**
**Electrical Resistance Summary** ** What is the journey of a typical electron? ** An electron is a charge carrier. Charge moves from high potential energy to low potential energy. The collisions of charge in an electric circuit with the conducting elements f the circuit result in a loss of energy. Each loss of potential is known as a voltage drop. Electrons travel in zigzag paths from one terminal of the battery to the other. ** What is resistance? ** An electron traveling through a circuit encounters resistance. Resistance is the hindrance to the flow of charge. The electrical potential difference between the two battery terminals encourages charge to move. The resistance discourages charge from moving. Things that affect resistance: length of wires, cross sectional area of wires, and material of which the wire is made. The conducting ability of a material is known as its resistivity. ** What is Ohm’s Law? ** (V = IR) Electric potential difference between two points on a circuit is equal to the product of the current between those two points and the total resistance of all electrical devices present between those two points. The current in an electrical device is directly proportional to the electric potential difference across the device, and inversely proportional to the resistance of the device. ** What is power (in terms of electricity)? ** P=VI Power is the rate at which electrical energy is supplied to a circuit or consumed by a load.

**Lesson 4:**
** What are circuit symbols and how do you draw circuit diagrams? **   Req = R1 + R2 + R3 + … Also, in a series the current is equivalent throughout. In a series circuit, there is only one pathway for charge to flow. In parallel, the sum of the current in the branches is equal to the current across the power supply. The equivalent resistance in parallel is always less than the lowest resistor. In parallel …. ** How do we determine current and equivalent resistance in combination circuits? ** By applying our knowledge of parallel circuits, we can transform the parallel circuit into a series circuit and then use our knowledge of series circuits to find the equivalent resistance.
 * Circuit Connections Summary**
 * What are the two types of connections? ** Resistors can be connected in series and in parallel. Adding more resistors in series will decrease the current because overall resistance increases. The bulbs will dim as more are added in series. Adding resistors in series will increase the current as the overall resistance of the circuit decreases. The bulbs will become brighter as more are added in parallel. [[image:Screen_shot_2011-11-10_at_11.56.29_AM.png width="800" height="385"]]
 * How do we determine the equivalent resistance and current in a series? **
 * How do we determine equivalent resistance and current in a parallel circuit? **