book+2,+2.4.notebook

IV. Electric Circuits A. Ohm's Law - resistance = to voltage/current 1. Resistance = voltage/current 2. Voltage = current x resistance 3. Factors that affect resistance are constant, resistance of most conductors on the voltage across them 4. Changing voltage in a circuit changes the current, but not the resistance 5. Most devices have constant resistance B. Features of a circuit 1. all electric circuits have some 3 basic features I. circuits have devices that are run by electrical energy a.) light bulbs and fans resist the flow of electric current 1.) represented as resistors in a circuit ii. circuit has a source of electrical energy a.) source of electrical energy makes charges move around a circuit, allowing the device to do work iii. electric circuits are connected by conducting wires a.) allow charges to flow from the energy source to the device that runs on electric current and back to the energy source. b.) switch often include in a circuit to control the current. 1.) used to open or close circuit 2.) turns device on or off C. series circuit 1. if all parts of an electric circuit are connected one after another along one path I. only 1 path for the current to take ii. disadvantages- goes out - they all go out a.) no other path to take ii. resistors - resistance increases as current decreases a.) if you add more light bulbs - light becomes dimmer b.) light bulb type of resistors 3. parallel circuits - different parts of the circuit are on separate branches I. several paths current to take ii. each bulb connected by separate path to battery and back iii. if one bulb goes out, rest stay lit iv. overall resistance increases v. add new branches, electric current has more paths to follow so resistance decreases vi. brightness of light doesn't change vii. new branches don't affect older branches 4. voltmeter - device used to measure voltage. or electrical potential energy difference 5. home - parallel circuits I. voltage - 120volts ii. heavy duty wires have low resistance circuit symbols wire- +- energy source ---0 0 switch 0resistor circuit diagram

series circuit parallel circuit