Chapter 13.1 ELECTRICITY AND MAGNETISM

Electric Charge  An electrical property of matter that creates a force between objects example: Touching a doorknob after walking across a rug on a dry day and getting shocked ELECTRIC CHARGE AND FORCE

 Like charges repel, and opposite charges attract  The two types of charges are called positive and negative  Ex. balloons  An object’s electric charge depends on the imbalance of its protons and electrons  Whenever there is an imbalance in the number of protons and electrons in an atom or molecule, it has a net electric charge. ELECTRIC CHARGE AND FORCE

 Conductors allow charges to flow; insulators do not  Conductors- a material that transfers charge freely  Insulators- a material that does not transfer charge easily  Objects can be charged by the transfer of electrons  When different materials are rubbed together, electrons can be transferred from one material to the other. ELECTRIC CHARGE AND FORCE

 Charges move within uncharged objects  The charges in a neutral conductor can be redistributed without contacting a charged object  Figure 13-4 ELECTRIC CHARGE AND FORCE

Electric force  Definition  The force of attraction or repulsion between objects due to charge  Electric force depends on charge and distance  The force between two charged objects varies depending on the amount of charge on each object and the distance between them.  Ex. The electric force between two balloons is proportional to the product of the charges on the balloons ELECTRIC CHARGE AND FORCE

 Electric force acts through a field  The region around a charged object in which other charged objects experience an electric force ELECTRIC CHARGE AND FORCE

13.2 CURRENT

Voltage and Current  Electrical potential energy  Potential energy of a charged object due to its position in an electric field  Potential differences is measured in volts  The change in the electrical potential energy per unit charge  There is a voltage across terminals of a battery\  Cell- a device that is a source of electric current because of a potential difference, or voltage, between the terminals CURRENT

 A voltage sets charges in motion  When charges are accelerated by an electric field to move a position of lower potential energy, an electric current is produced.  Current- the rate that electric charges move through a conductor  Conventional current is defined as movement of positive charge  Conventional current- the current made of positive charge that would have the same effect as the actual motion of charge in the material. CURRENT

Electrical Resistance  The difference in current between bulbs of different voltages is due to resistance.  Resistance- the ratio of the voltage across a conductor to the current it carries  Resistance can be calculated from current and voltage  Resistance equation  Resistance= voltage or R = V current I CURRENT

 Pg. 436, #1, 2, 4  Pg. 443, #1-4  Pg. 445, #7, 8 CLASSWORK/HOMEWORK

13.3 CIRCUITS

Electric circuit  An electric circuit is a path through which charges can be conducted  An electrical device connected so that it provides one or more complete paths for the movement of charges  Some circuits include a switch (opens and closes a circuit) ex. Light switch CIRCUITS

 Schematic diagrams are used to represent circuits  Schematic diagram- a graphic representation of an electric circuit or apparatus, with standard symbols for the electrical devices CIRCUITS

Series and Parallel Circuits  Series circuits  A circuit or portion of a circuit that provides a single conducting path  Parallel Circuits  Components in a circuit that are connected across common points, providing two or more separate conducting paths CIRCUITS

Electric Power and Electrical Energy  Electrical energy  The energy associated with electrical charges, whether moving or at rest  Power= current x voltage or P= IV CIRCUITS

 Fuses melt to prevent circuit overloads  Fuses- an electrical device containing a metal strip that melts when current in the circuit becomes too great  Circuit breakers open circuits with high current  Circuit breaker- a device that protects a circuit from current overloads CIRCUITS

 CIRCUITS