SPH3U-F

12.1 Electrostatics - the electrical structure of matter / atoms, protons, electrons, neutrons, ions, e is the elementary charge on a single particle - the basics of electrostatics / fundamental laws of electric charges (opp attract, similar repell, charged can attract some neutral) - charging an object / insulators, conductors - charging by friction - electroscopes / pith ball, metal-leaf - charging by contact - charging by induction - controlling static charges in a clean room

12.2 Electric Fields and Electric Charge - electric fields - measuring electric charge / Coulomb’s law (F = kQ1Q2/d2), Millikan’s oil drop experiment – e = 1.6 E-19 C, Q = Ne where Q total charge on object, N is excess or deficit number of electrons

12.3 Electric Current - I (amperes) = Q (Coulombs) / t (seconds) –passing through a cross section of a conductor: 1A = 1C/s - the direction of electric current / current is defined as moving from positive terminal to negative terminal, which is the opposite direction of electron flow - in solids, electrons flow; however, in liquids or gases, negative and/or positive charges can flow - batteries supply DC, wall outlets supply AC - ammeter used to measure current

12.4 Electric Potential Difference - V (volts) = Work (Joules) / Q (Coulombs) – electric potential difference between two points is the work required to move the electric charge (Q) between the points: 1 V= 1J/C - voltmeter used to measure electric potential difference - the electrical energy lost by a current I through a voltage potential V for a time t is represented by the equation E=VIt

12.5 Kirchoff’s Laws - circuit symbols - series circuits - parallel circuits - law of conservation of energy – sources supply energy, loads lose energy, net energy gained/lost in the system must be zero - law of conservation of charge – electric charge is not created nor lost in a circuit, nor does it accumulate at a point - Kirchoff’s voltage law – around any complete path through an electric circuit, the sum of the increases in electric potential is equal to the sum of the decreases in electric potential - Kirchoff’s current law – at any junction point in an electric circuit, the total electric current into the junction is equal to the total electric current out.

12.6 Electric Resistance - Ohm’s law – potential difference between any two points in a conductor varies directly with the current between the two points if the temperature remains constant: R (ohm) = V / I (1 W = 1 V/A) - resistance in series Rt = R1 + R2 + … + Rn - resistance in parallel 1/Rt = 1/R1 + 1/R2 + … + 1/Rn - electric circuit analysis

12.7 Power in Electric Circuits - The rate at which a device uses energy is known as power, represented by the equation P=VI or P = I2R or P = V2/R - cost of electricity – power measured in kWh: multiply by number of hours and then by rate to get cost

13.1 Magnetic Force and Fields - law of magnetic poles: opposites attract, similar repel - the space around a magnet in which magnetic forces are exerted is known as the magnetic force field - the magnetic force around a bar magnet is three-dimensional in nature

13.2 Magnetic Materials - domain theory of magnetism

13.3 Oersted’s Discovery - principle of electromagnetism: whenever an electric current moves through a conductor, a magnetic field is created in the region around the conductor in concentric circles - right hand rule for a conductor: if a straight conductor is held in the right hand with the thumb pointing in the direction of the electric current, the curled fingers will point in the direction of the magnetic field lines

13.4 The Magnetic Field in a Coil or Solenoid - right hand rule for a coil: if a coil is grasped in the right hand with the curled fingers representing the direction of electric current, the thumb points in the direction os the magnetic field inside the coil - factors affecting the magnetic field of a coil, including relative magnetic permeability (K) = magnetic field strength in material / magnetic field strength in vacuum (doubling permeability doubles field strength) - ferromagnetism, paramagnetism, and diamagnetism - applications of electromagnetism (lifting, relay, electric bell)

13.5 Conductor in a Magnetic Field – The Motor Principle - motor principle: a current carrying conductor that cuts across external magnetic field lines experiences a force perpendicular to both the magnetic field and the direction of the electric current. The magnitude of the force depends on the magnitude of both the external field and the current, as well as the angle between the conductor and the magnetic field it cuts across. - right hand rule for the motor principle: if the fingers of the open right hand point in the direction of the external magnetic field and the thumb represents the direction of the electric current, the force on the conductor will be in the direction in which the right palm faces - coulomb defined in terms of current causing force between two wires: SI definition of Coulomb is 1 C is the amount of charge flowing past a point in 1s when the current is 1A (1C = 1 As)

13.6 Applications of the Motor Principle - moving-coil loudspeaker - moving-coil galvanometer - electric motor - magnetic resonance imaging (MRI)

14.1 Faraday’s Discovery Although a steady current in a conductor produces a steady magnetic field, a steady magnetic field does not product a current in a conductor - faraday’s law of electromagnetic induction: an electric current is induced in a conductor whenever the magnetic field in the region of the conductor changes / if the magnetic field inside a coil changes amount or changes direction, an electric current is induced in the coil - mutual induction occurs whenever a changing current in one coil induces a current in a nearby coil - the magnitude of an induced current in a coil is affected by the number of turns on the induction coil, the rate of change of the inducing magnetic field and the strength of the inducing magnetic field.

14.2 Direction of Induced Current - Lenz’s Law of Induced Current: for a current induced in a coil by a changing magnetic field, the electric current is in such a direction that its own magnetic field opposes the change that produced it. - how a television tube (cathode ray tube) works

14.3 Electric Generators: AC and DC - the AC electric generator - the DC electric generator - maximizing output from AC and DC generators - electric generating stations

14.4 The Transformer - step up and step down transformers - secondary potential diff / primary pot diff = sec. windings / primary windings - V(sec) / V (pri) = N(sec) / N(pri)

14.5 Distribution of Electrical Energy - power loss less at higher voltages - magnetic information storage