Home > Courses > 1P22_Crandles Electromagnetism, Optics, and Modern Physics Introduction Oscillations and waves Electrostatics Electric circuits Microscopic Model for Current Current is a movement of charge Average Velocity in presence and absence of Applied Electric Field Current and Drift Velocity Ex: Calculate this drift velocity Conventional Current versus Electron current Voltage, Batteries and Electric Field Resistance Resistance defined phenomenologically: Ohm's Law: I=V/R MC: Current and Voltage Ex: electric socks defined through material's properties: R = rho L/A Construction of a Carbon resistor Table of resistivities MC: Resistance and diameter MC: Resistance and Length MC: How does current change I? MC: How does current change II? Not all devices- obey Ohm's Law Simple electric circuits dc voltage versus ac voltage Resistors: ac current and voltage are in phase Energy/power in electric circuits Ex: burning up resistors instantaneous power loss in a resistor RMS voltage and average power Cost of electricity: ontario hydro rates Resistors connected in series and in parallel: Equivalent Resistance Kirchhoff's voltage rule (KVR) Kirchhoff's current rule (KCR) MC: Which resistors are connected in series ? MC: Which resistors are connected in parallel ? MC: bulbs in series versus bulbs in parallel MC: electrical "short" Ex: simple circuit reduction Voltage divider Ex: current dividers MC: current divider MC: KVR MC: unscrewing bulbs I MC: unscrewing bulbs II Ex: circuit reduction II Ammeters and Voltmeters A galvonometer is part of analog ammeters and voltmeters A model galvonometer is characterized by "full scale deflection" and coil resistance A real analog ammeter consists of a galvonometer and small shunt resistors. A real analog voltmeter consists of a galvonometer and large series resistors. An ideal ammeter has zero resistance and is connected in series An ideal voltmeter has infinite resistance and is connected in parallel. Capacitors in electric circuits Charging a capacitor: Voltage grows while current decreases Discharging a capacitor: Both voltage and current decrease Ex: Discharging a capacitor MC: What happens to the RC time constant? Ex: Charging a capacitor Magnetism, induction and ac circuits Wave Optics Quantum Physics