Electricity 2 objectives

Bill Nye video “Electricity” Crossword

Electric Potential Energy Stored electrical energy Ex. A battery has stored electrical energy because the electrons have the ability to do work after they leave the battery.

Electric Potential Difference The change in potential energy per coulomb of charge. Also called voltage Measured in volts (V) Measured using a voltmeter

Electric Charge A building up at the negative terminal of a cell/battery which then flows from this terminal as negative charges repel one another.

Electrochemical cell & Electric Charge Two types of electrochemical cells – dry cells (battery in a flashlight) and wet cells (battery in a car) Both types produce voltage

Electrochemical Cell An electrochemical cell is a device or a mechanism that can either generate electrical energy from a chemical reaction or utilize electrical energy to produce a chemical reaction.

Electrochemical cell

Electrochemical cell is made of; 2 electrodes usually made of different metals The electrodes are in an electrolyte, which is a substance that conducts electricity Dry cell – electrolyte is a paste Wet cell – electrolyte is a fluid

How it Works The acidic electrolyte attacks the zinc electrode and pulls atoms off the zinc. But the zinc atoms leave electrons behind on the electrode, and the electrode becomes negatively charged At the same time, chemical reactions pull electrons off the copper electrode Therefore the copper electrode has a positive charge. Because there is an opposite charge on each electrode, there is a potential difference (voltage) between the two electrodes.

Electric Circuit A complete pathway that allows electrons to flow. Will transform electrical energy into other forms of energy.

Parts of an Electric Circuit

Describe the parts of an electric circuit; Source of electrical energy Electrical load Control / switch conductor

Electric Current The amount of charge passing a given point in a conductor per second. Measured in amperes (A) Measured using an ammeter

Flow of Electric Current

Current Electricity The continuous flow of charge in a complete circuit.

Circuit Diagrams

Circuit Diagram Symbols: Page 262 Bulb Cell Battery Wires Resistors Ammeter Voltmeter Open / closed switch

How to Draw a Circuit Diagram

Worksheets Drawing circuit diagrams How to make light bulbs glow

Potential energy is stored energy In a circuit, the battery stores energy (source of the potential energy). Once it is connected to a light bulb, the electric potential energy is “released”. As the electrons move through the wire inside the bulb, the electrons energy is converted to heat and light energy.

Electrical Resistance Slows down the flow of electrons and converts electrical energy into other forms of energy. Measured in ohm’s (Ω) The ratio of the voltage to the current.

Factors affecting resistance in a wire Length Diameter Type temperature

Resistors Used to control current or potential difference in a circuit.

Textbook Page 277 Resisters Values Worksheet

Ohm’s Law The mathematical relationship comparing voltage (V), current (I) and resistance (R) V I R

Calculate Voltage, Current, & Resistance Practice Problems Page 273-274 Worksheets – calculating voltage, current, and resistance.

Lab Page 278-279