Mr. Gillis’ Science Class

What needs to happen to get the bulb to light?

 Connectors  Energy source  Control Device  Ex. switch  Load

 Place the bulb in a socket  Use one D cell  Make the bulb light!  Add a switch to conserve D cell energy  Use your finger to trace the path of electricity from one terminal of the D cell to the other terminal

 Wire  Bulb  Battery  Switch Symbols used for Diagramming

 1. Static electricity is an electric charge that remains in a fixed position or region on an object. Current electricity is an electric charge that is moving in one or more paths. The moving electric charge is called an electric current. The electric current may be flowing in an uncontrolled path (lightning) or a controlled path (electric circuit). ..

Part of the CircuitFunctionExamples Source of electrical energy Provide energy to the electric load in the circuit Battery, 120V source Electric loadConvert electrical energy into another form of energy Light bulb, motor Electrical control device To control the flow of electric current in the circuit Switch, fuse ConnectorsTo provide a conducting path between the parts of a circuit Connecting wires, copper strips

 3. The electric charge flows from the negative terminal of the dry cell (yellow wire), through the switch, the bulb and back to the positive terminal of the dry cell (green wire). Negative charges are released at the negative terminal and are attracted toward the positive terminal.

ENERGY (E) – the ability to do work  There are many forms of Energy kinetic, mechanical, chemical, solar...

KINETIC ENERGY POTENTIAL ENERGY  Energy of motion  stored Energy ex: spring, elastic band

 When + and – charges are pulled apart there are attractive forces wanting to put them back together, this is a form of potential energy as it has the ability to do work!

Stored electrical energy such as that stored in a battery

 Converts: Chemical Energy into Electrical Energy  + and – charges are separated into terminals located at either end of the cell, when connected – charges (electrons) travel towards the + (positive) terminal as the – charges repel one another

 Batteries have electric potential Energy because the stored e-’s have the ability to do work, i.e. run your CD player!

 different electrodes (usually metals also Carbon)  And an electrolyte (electrolytic solution)

Change in potential energy per coulomb of charge Measured in volts (V) by a voltmeter

 1)a) The electrons must move continuously around the circuit to continually provide electrons from the circuit to the positive terminal on the dry cell for chemical reactions to occur inside the dry cell.  b) The electrical charges flow from the negative terminal of the dry cell into the circuit. When the chemical reactions occur inside the cell, the electrons are released at the negative terminal (electrode).

 2)a) Electric potential (voltage) is the energy each electron has as it leaves the negative terminal of the dry cell.  b) The SI unit for electric potential (voltage) is the volt, and the symbol for the volt is V.  3)When the dry cell is actually made, a limited number of chemical reactions occur that release electric charges that accumulate on the negative terminal of the dry cell.

 4) The voltage of an electrical energy source is a measure of the energy of the individual electrons at the negative terminal, compared to the positive terminal. The voltage of the electrons at the negative terminal of a 120-V source is 20 times greater than that of electrons at the negative terminal of a 6-V battery. This extra amount of energy per electron is sufficient to give someone a severe electric shock.

 Stairs = the voltage  Backpack = amount of charge separated  More work has been done in B, therefore it has a greater Potential Energy!

Electric Circuit  A complete pathway that allows electrons to flow  Transforms electrical energy into other forms of Energy  Interactive website Interactive website

Conductor – wire through which current flows Load – converts electrical E into other forms of E Switch – turn circuit on or off Source – source of electrical E Interactive Website on Switches

the amount of charge passing a given point in a conductor per second measured in amperes (A) by an ammeter or (mA) by a galvanometer

Electrical Resistance:  Slows down the flow of electrons and transforms electrical E into other forms of E Electrical E  Light  Heat  Sound  Motion  etc

Measured in ohms (Ω) Equal to the ratio of the voltage to the current R = V/I

Current Dependent on Potential (voltage) Current Dependent on Resistance

1. Length 2. Diameter (thickness) 3. Type of wire 4. Temperature

 Long, Thin Tungsten wire  Short, Thick copper wire

The Mathematical Relationship comparing voltage (V), current (I) and resistance (R) V = I ● R Interactive website

V I R

V=I●R I = V R R = V I Where:  V = voltage measured in volts (V)  I = current measured in amperes (A)  R = resistance measured in ohms (Ω)

V=I●R I = V R R = V I Where:  V = voltage measured in volts (V)  I = current measured in amperes (A)  R = resistance measured in ohms (Ω)

STEP 1: Read and reread the question. Step up variables with known information. V = ? I= 0.5A R= 2Ω Use a question mark for the unknown value you are trying to find. Be sure to include units (V,A,Ω)

STEP 3: Convert units if necessary, measurements must be in V for voltage, A for current and Ω for resistance. Fill in the information given in the question (including units).

V =I●R V = (0.5A)(2.0Ω) V= 1.0 V The flashlight would require a voltage of 1.0 V.

Used to control CURRENT or potential difference ( VOLTAGE ) in a circuit

 Add a second D cell to your circuit, right next to the first. Be sure to match up positive terminal with negative terminal  Do you notice any difference?  Add a second light bulb to the circuit, keeping only one pathway for electricity to follow  What do you observe now?

 Keep two D cells in the circuit  Wire up the 2 light bulbs so that there are two branches or pathways for electricity to follow  What differences do you observe?

Inverse Relationship

The amount of potential energy that each unit of charge has

 V = voltage, measured in volts  I = current, measured in amperes, or amp  R = resistance, measured in Ohms, symbol 

Battery by itself  Battery in a circuit

 Multimeter completes the circuit  Current in a circuit

 How does changing resistance affect current?  How does changing voltage affect current? Investigating Ohm’s Law

 Current decreases when resistance is increased How does changing resistance affect current?

 Voltage/Current = Resistance How does changing voltage affect current?

 Rise/Run = Slope  Voltage/Current = Resistance

 If two of the quantities involved are known, the third can be determined mathematically  I = V/R  V = IR  R = V/I

Series Circuit Parallel Circuit

 Can we measure these values in a circuit?  As we measure these values, do they change in relation to one another

 Resistance of a bulb  A measure of conductivity