Aim: How do we analyze a series circuit? HW: Problem Set

Combine Ohm’s Law and Power Law Recall earlier equation for power… Power Equations Combine Ohm’s Law and Power Law Recall earlier equation for power… Relate to POWER Rangers… get it? Because they are POWER and morph… like equations… yea.

Circuit Types Draw a standard simple circuit with all the pieces that make it tick. What’s strange about this diagram? Conventional current

Conventional Current The direction that positive charge would flow equal to electron flow.

Circuit A path through which current flows from an area of high voltage to an area of low voltage. How does this make sense? From electrostatics: Negative charges flow from low to high potential. Positive charges flow from high to low potential. Conventional current is a measure of positive charge flow, which goes high to low!

Circuit Element Review Other Elements Resistances Measurement Devices Voltage sources Fixed resistor – resistance does NOT change once installed Opens and closes the circuit turning current flow on or off Resistance CAN be changed after installation Voltmeter is a device for measuring VOLTAGE How hard are electrons being pushed? Ammeter is a device for measuring CURRENT How many electrons flow per second? Provide electrical potential for electrons – “PUSHING” or “PUMPING” them through the circuit Special resistor – used to produce light!

Measurements V V V A A V 100V R = 10Ω 0V 0V 10A 10A Voltmeter measures RELATIVE differences from OUTSIDE the circuit Ammeter measures flow INSIDE the circuit V = 100V V 100V

PRELIMINARY SUMMARY Name and draw 8 of the circuit elements How is the voltmeter connected to a circuit? How is an ammeter connected to a circuit?

Two types of Circuits Series Circuit: When two or more resistors connect end-to-end in series with each other forming a loop. Parallel Circuit: Current from the power source splits into separate branches such that the resistors are not in series, but parallel.

Series Circuit A circuit composed of two or more resistors connected end-to-end, creating a SINGLE LOOP

Series Rules ITotal = I1 = I2 = I3 = …= IN The equivalent resistance for a series circuit is the SUM of all RESISTANCES in the circuit RTotal = R1 + R2 + R3 + …+ RN The total voltage in the circuit is equal to the SUM of the VOLTAGE DROPS across the resistors. VTotal = V1 +V2 + V3 + …+ VN The current in the circuit is constant at ALL points in the circuit. ITotal = I1 = I2 = I3 = …= IN All COMPONENTS and the WHOLE CIRCUIT obey OHM’S LAW

Req = R1 + R2 + R3 = 400Ω 100 Ω 75 Ω 225 Ω R1 R2 R3 10 V I = V / R I = 0.025 A 10 V

VIR Chart V I R R1 R2 R3 Req 100Ω 75Ω 225Ω 10V 0.025A 400Ω 0.025A 2.5V

50 Ω 120 Ω 150 Ω R1 R2 R3 1.5A ? V

VIRP Chart V I R P R1 R2 R3 Req 50Ω 120Ω 150Ω 1.5A 75 V 1.5A 180 V 112.5W 180 V 1.5A 270.0W 225 V 1.5A 337.5W 480 V 320Ω 720W

SUMMARY What does a series circuit look like? In a series circuit, what are the rules for… Current? Voltage? Resistance?