Where Does Current Come From? - UMass D

Where Does Current Come From? - UMass D

Where Does Current Come From? The free electrons in a conductor need to be replaced when they move through the conducting medium (the wire). These electrons are replaced by electrons from a source of energy such as a battery. EGR 101 1 Circuit Components

Batteries + + EGR 101 2 Source of Voltage in a Battery A chemical reaction within the battery

separates positive and negative ions (charged atoms) When the battery is connected to a circuit, the negative charges move toward the positive terminal and a current is produced The amount of current is constrained by the resistance of the circuit EGR 101 3 Example of A Battery

The source of energy E in (Joules) releases charges Q in (Coulombs) Voltage (V) the difference in potential that uses E = one Joule (J) of energy to move a charge Q = one coulomb (C). EGR 101 4 Current Direction We will adopt Conventional Flow for all of our work!

EGR 101 5 Mathematical Relationship E: Energy required to move charges in Joules (J). Q: Charge value in Coulombs (C). V: Voltage or potential difference across the battery's posts in volts (V). Thus, V = E / Q.

In units: 1 Volt = 1 Joule/Coulomb EGR 101 6 Team In-class Activity (15 minutes) A 10 V source uses 2 Joules of energy per second. Calculate the current being used by the source. Hint, turn the word problem into equations; write down what you know.

EGR 101 7 When batteries are connected with their polarities in the same direction, they are in a series-aiding arrangement. EGR 101

8 When batteries are connected with their polarities in the opposite direction, they are in a seriesopposing arrangement. EGR 101 9

In Class Activity What is the total voltage between terminals A and B in the figure below? A B 9V 4V 15V

Which terminal is at a higher potential? EGR 101 10 Introduction to Ohms Law A 1 Ohm resistance limits the current to 1 Amp when 1 Volt is applied. V = I. R EGR 101

11 Ohms Law V IR Three forms: V I R V

R I Use the form that best describes the quantity that you are trying to determine EGR 101 12

Determine the Current I + _ V I R EGR 101 13

Determine the Voltage + _ V IR EGR 101 14 Determine the Resistance + _

V R I EGR 101 15

Recently Viewed Presentations

  • Introduction to Financial Management

    Introduction to Financial Management

    CFFA_2. CFFA_1. Net sales. Cost of goods sold. Depreciation. EBIT. Interest paid. Taxable income. Taxes. Net income. Dividends. Addtion to retained earnings. 2010 Income Statement. DOLE COLA. 2010 Operating Cash Flow + Depreciation - Taxes. 2010 Net Capital Spending. Ending...
  • 24.5 Fatty Acid Synthesis When the body has

    24.5 Fatty Acid Synthesis When the body has

    HS — ACP contains the thiol and pantothenic acid (vitamin B 5) groups found in acetyl CoA attached to a protein. Preparation of Activated Carriers. Before fatty acid synthesis can begin, the activated carriers must be synthesized.
  • Unless otherwise noted, the content of this course

    Unless otherwise noted, the content of this course

    If we apply an external, oscillating force that serves to "drive" the system at some driving frequency fd, then the system is able to absorb energy via the work done by the driving force. The condition known as resonance is...
  • Work in progress: Lichen substrate ecology of the

    Work in progress: Lichen substrate ecology of the

    Casual field observations suggest that high elevation sites in the "mist belt" support a diverse assemblage of lichens that are relatively undifferentiated across substrates, and that at lower elevations, the relatively harsh conditions on rock surfaces result in an overall...
  • Chapter 6 Mobile Computing and Commerce and Pervasive

    Chapter 6 Mobile Computing and Commerce and Pervasive

    Chapter 6 Mobile Computing and Commerce and Pervasive Computing Learning Objectives Describe the mobile computing environment that supports m-commerce (devices, software, services).
  • Processes of Communication

    Processes of Communication

    Processes of Communication Sender-Receivers Receive-Senders Pop Quiz context physical environment climate communicator message channel noise barrier feedback Person is speaking French to you, but do not speak French Billboard sign Having a cold Prejudice Tension within a room Communication Cycle...
  • Oporná sústava - kostra

    Oporná sústava - kostra

    Oporná sústava - kostra = sceletum pasívny pohybový aparát, prepojený so svalmi opora tela ochrana dôležitých orgánov ( mozog, miecha, pľúca, srdce)
  • Kinematics The study of motion in One Dimension

    Kinematics The study of motion in One Dimension

    * Kinematics The study of motion in One Dimension Unit 2 Motion Relative motion Quantifying Motion Scalar vs. Vector Speed vs. Velocity Distance vs. Displacement Acceleration Kinematic equations Graphical interpretation of motion Free fall motion Classification of Physics Quantities Vector...