Electric Forces simulationsUnlike Gravitational Fields with only one type of mass to act upon, Electric Fieldshave two types of charge that they can make an Electric Force on: POSITIVE andNEGATIVE. http://phet.colorado.edu/en/simulation/travoltage http://phet.colorado.edu/en/simulation/balloons or CLICK ON THE PICTURE or CLICK ON THE PICTURE Use these two simulations to see how electric charges behave. Notice which one can move and which one can’t?
Charges (Q) – measured in Coulombs The Law of Conservation of Charge (Q) Charge can neither be created nor destroyed.
Electric FieldsAn electric field is a region of spacewhere a charged object experiencesa force due to its charge.Field LinesBecause there are two charges that move in different directions in a field it has beendecided that Field Lines should show the direction that a POSITIVE charge wouldaccelerate if placed in the field.
Electric Fields (more examples) The arrows are always showing the direction that a POSITIVE charge would move in the field.
Electric Fields simulations Charges and Fields Electric Field Hockeyhttp://phet.colorado.edu/sims/charges http://phet.colorado.edu/en/simulation/-and-fields/charges-and-fields_en.html electric-hockeyUse these two simulations to see how the field lines work for differentcharges.
Coulomb’s Law Newton’s LawThe Force between two point The Force between two pointcharges is directly proportional to masses is directly proportional tothe product of the CHARGES and the product of the MASSES andinversely proportional to the inversely proportional to thesquare of their distance apart. square of their distance apart. k= 9 x 10-9 Nm2C-2 G= 6.6742 x 10-11 m3kg-1s-2
Electric Field Gravitational Field Strength StrengthDefinition: Definition:The force per unit charge The force per unit massexperienced by a small positive experienced by a small test masstest charge placed in the field. placed in the field. Units: NC-1 Units: NKg-1Example:
Electric Field around a sphere of charge QBecause Field Strength is a vector it can be added usingVector addition just like Gravitational Field Strength