Electricity Chapter 11 Quiz Notes PDF

- Circuit components (ie. load, source, cell, resistor etc.) - Definitions and symbols - Drawing combination circuits (loads in both series and parallel combined in one circuit) - Current and Potential difference - Definitions - The rules for each, in series and in pa...

- Circuit components (ie. load, source, cell, resistor etc.) - Definitions and symbols - Drawing combination circuits (loads in both series and parallel combined in one circuit) - Current and Potential difference - Definitions - The rules for each, in series and in parallel - Taking readings from ammeters and voltmeters - Determining voltage and current at loads in combination circuits. - Using Ohm’s Law, V = IR to solve for either voltage, current or resistance. 11.1 Current Electricity and Circuits Circuit: a path for electron flow Current Electricity: a continuous flow of electrons in a circuit Load: a device that converts electrical energy to another form of energy - Example: light bulb, motors, fans Switch: a device that can turn the circuit on and off by closing or opening the circuit - Open circuit means no flow of electricity Electrochemical Cells Battery: a combination of electrochemical cells Electrochemical Cells: a package that converts chemical energy into electrical energy Electrolyte: a liquid or paste that conducts electricity because it contains ions Wet Cell: liquid electrolyte - Example: car battery Dry Cell: electrolyte paste - Example: battery Electrodes: metal strips that react with the electrolytes Dry Cell Recycling and Recharging - Dry cells will get used up and must be discarded. - They contain toxic material so you shouldn’t send them to landfill. - There is special recycling for batteries - Some dry cells are rechargeable. - Chemical reactions in rechargeable batteries are reversible. - Using rechargeable batteries are better for the environment Fuel Cell: Electrochemical cell that generates electricity directly from a chemical reaction with a fuel Potential Difference Measurement Potential Energy: energy stored in an object Potential Difference (Voltage): the difference in electrical potential energy between two points in a circuit - Measured with a voltmeter using volts (V) - Must be connected across a source or load  - Known as “V” Electron Transfer Energy in a Circuit - Electrons travel through a conductor like a wire like balls through a tube. - Electrons push or repel nearby electrons. - Electrons are stored in the wires and ready to turn on electricity as soon as you turn on the switch. - There are 2 ways to show flow, we will use electron flow Current Electrical Current: the measure of the amount of electric charge passing a point in an circuit - Measured with an ammeter using amps/amperes (A) - Must be connected in the path of circuit - Current is known as “I” Direct Current (DC): the flow of electrons in one direction - Example: batteries Alternating Current (AC): flows back and forth at regular intervals called cycles - Example: generators, power lines Electron Flow, Conventional Current - Flow of electrons is from negative to positive terminal - Conventional current flows from positive to negative terminal - Always connect positive to positive and negative to negative Resistance Resistance: the degree to which a substance opposes the flow of electric current - All materials have resistance, some more than others - Even wires have resistance - a load or a resistor will slow down electron flow (decrease current) - When a substance resists the flow of electrons it slows the current and converts it to some other form of energy - Can be loads - Example:light bulb, motors, fan - Measured with an ohmmeter using ohms (𝛺) - Known as “R” Resistor: any material that slows current flow - High resistance causes electrical energy to converts to light or heat energy Factors Affecting Resistance in a Wire Materials: copper is a good conductor Temperature: resistance increases as wire gets warmer Length: longer wires have more resistance Thickness: Wider wires have less resistance than thin wires 11.2 Types of Circuits Series Circuit: one path for electrons to flow Parallel Circuit: more than one path for electrons to flow Circuit Potential Difference (V) Current (I) Resistance (R) Series Must add up to be the Same through each load The current same as the source as through the source decreases when (battery) more resistors are added. Parallel The voltage at each Must add up to be the Adding resistors load must be the same current going to the decreases the total as the source (battery) main source resistance of the circuit 11.3 Relationship of Potential Difference, Current, and Resistance - The higher the resistance, the lower the current - The higher the resistance, the higher the voltage required to get the same current - The higher the voltage, the higher the current Ohm’s Law Voltage (V) = Current (I) x Resistance (R) I=V/R R=V/I - A milliampere (mA) = 0.001 A