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Published byFelix Curtis Modified over 8 years ago
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WARM UP Two negative charges, one twice as large as the other, are located 0.05 m apart and experience a repulsive force of 5 N. What is the magnitude of the larger charge? How many excess electrons are on the object with less charge.
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Physics Honors A/B –Day 3/07/16 & 3/08/16 Electrical currents and Circuits
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Agenda Current Voltage Sources Resistors Simple Circuit Build a simple circuit
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Create a simple circuit Make a simple circuit with 1 battery, 1 bulb and wires.
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Why should we study circuits?
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Where is electrical current in real life?
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Electrical Current All Electrical circuits have one thing in common They have an Electrical Current Electrical current The amount of charge that flows is a given period of time So what’s flowing?
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Electrical Current Flow of current Flow of water analogy
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Electrical Current
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Example Problem An iphone runs off a current of 0.22 A. How many electrons pass through the iphone in 5 secs?
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Voltage Source Voltage Source needed to drive the current through the circuit Two types Direct Current Circuits Constant Current Constant Voltage Alternating Current Circuits Changing Current Changing Voltage
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Electric Potential is related to Electric Field
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DC Circuit Battery uses chemical reaction to produce a difference in electrical potential between it’s terminals When connected to a circuit, electrons move in a closed path from one terminal through the circuit and back to the other side of battery
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Path of Electrons in a Circuit CORRECT Electrons leave from the negative terminal of the battery and return to the positive Path is chaotic and slow like couple of cm/s
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Resistance is affected by several factors FactorLower ResistanceHigher Resistance Material Length Area Temperature
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Ohms Law
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Electric Circuit Symbols Need these symbols to draw schematic of circuit Make this simple circuit then draw a schematic to represent this circuit
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Electric Circuit Symbols Build this circuit with 3 lamps and 2 batteries and 3 switches
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Voltmeter and Ammeter Voltmeters – measure voltage between any two points in the circuit Connected across the resistor, or device, voltage drop is to be measured Ammeter – measures current through the particular point in the circuit it is connected Connected in the circuit
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Electric Circuit Symbols Measure the voltage across the battery Measure the voltage across each of the bulbs Measure the current after each of the bulbs
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Electric Circuit Symbols Need these symbols to draw schematic of circuit Build and Design 3 different simple circuits with 3 lamps, switches and batteries On a separate sheet of paper – Turn in the box Draw one version without symbols Redraw with symbols
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Semiconductors are the exception to the rule Semiconductors are insulators but when impurities are added they become conductors Doping Depending on impurity, become different kind of conductors N-type have electrons as charge carriers P-type have positive charge carriers called “holes” Temperature increases; resistivity decreases
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