 Electric Circuits:

Objectives:

1.    Describe the configuration of a working circuit.

2.    Distinguish between a parallel and series circuit.

3.    Describe the characteristics of series connections and of parallel circuits.

4.    Given I, R, or V be able to calculate ohm's law through a circuit.

Key Terms.

Notes:

Electric Circuits:

An electric circuit provides a complete, closed path for electrons to travel from one charged pole to the other.  It is important to remember that electricity can NEVER flow through an open circuit.

Parts of a Circuit Consists of 4 parts

2.       Conductor - Wire

3.       A switch

4.       A source of electrons                                (www.doctronics.co.uk/ images/circ1.gif)  The source can be an electrochemical (DC), thermocouple (DC), or a generator (AC). The load is anything that uses electric energy - appliance, light bulb, ... The switch opens and closes the circuit.

Series Circuit:

In a series circuit, electrons flow from the anode through each load and back to the cathode.   This is similar to many old Christmas light sets.  If one bulb burned out the whole strand stopped working.  The burned out bulb created an open circuit. There is no way for the current to go around each device. The resistance adds up with each device that is added The total resistance is always greater than the largest resistor The voltage drops with each device that is added The current remains constant and is based on the total resistance and voltage  (www.physics.udel.edu/.../phys208/ images/series-circuit.gif)

(www.berkeleypoint.com/ images/series.jpg) Bulbs decrease in brightness as they move away from the anode

 Ohm's Law - Series Current (I) I(total) = I1 = I2 = I3 Voltage (V) V(total) = V1 + V2 + V3 Resistance (R) R(total) = R1 + R2 + R3

Parallel Circuits:

In a parallel circuit, electrons flow from the anode through, and around each load and back to the cathode.   This is similar to the way your house is wired.  If one bulb burns out the rest of the outlets in the house remain operational.  The burned out bulb does not created an open circuit. There is a way for the current to go around each device. The total resistance is the reciprocal of the 1/the total resistance The total resistance is always less than the smallest resistor The Voltage remains constant and is based on the total resistance and current The current drops with each device that is added (www.ibiblio.org/obp/electricCircuits/ DC/00083.jpg) (www.berkeleypoint.com/ images/series.jpg) All bulbs are equally bright

 Ohm's Law - Parallel Current (I) I(total) = I1 + I2 + I3 Voltage (V) V(total) = V1 = V2 = V3 Resistance (R) 1/R(total) = 1/R1 + 1/R2 + 1/R3