JC Technology Electric Circuits

Electric Circuits Computers CD Player IPhone How do they work? IPhone – Charge battery and turn on All use Electricity – part of electric circuit Plug in and turn on

Electric Circuits Loop/path/route – connects device to a power supply Device turned on – electric current flows around the loop Device works Simple Circuit Battery = Power supply Switch opens & closes circuit

Electric Circuits Circuit Diagrams – symbols are used to represent components =

Electric Circuits Electric Current: The flow of electrons through a conductor Conductor – materials that allows current to flow through it examples: copper, gold, silver, tin, iron Electron – negative charge Nucleus: neutrons – no charge protons – positive charge Copper Atom

Electric Circuits Electron on outer shell of atoms can move between atoms No power supply - movement is random conductor

Electric Circuits Conductor connected to power supply: Electrons all move in same direction – electric current

Electric Circuits Measuring electric current – Ammeter Ammeter must be connected correctly Unit of measurement = Ampere (A) or amp Represented by letter I

Electric Circuits Electromotive Force (EMF) – force that makes electrons flow around a circuit Unit of measurement = Volt EMF often called Voltage Higher voltage = more current

Electric Circuits Voltage is represented by letter V Measured using a voltmeter

Electric Circuits Resistance: opposition to the flow of electric current All components have resistance Unit of measurement = Ohm (Ω) Represented by letter R High resistance = less current

Ohm’s Law ‘The electric current in a conductor is directly proportional to the applied voltage and inversely proportional to the resistance at constant temperature’ increasing voltage increases current increasing resistance decreases current Ohm’s Triangle

Ohm’s Law

Series Circuit Components are connected one after the other Only one path for current to flow around All components on or off at same time

Series Circuit The current at all points in a series circuit is the same

Components of equal resistance – voltage is shared equally Series Circuit The applied voltage is shared between the components Components of equal resistance – voltage is shared equally B1 = B2

Components of unequal resistance – voltage is shared proportionally Series Circuit The applied voltage is shared between the components Components of unequal resistance – voltage is shared proportionally B1 ≠ LED

Series Circuit Voltage across each component depends on its resistance High resistance = high voltage share Low resistance = low voltage share

Series Circuit Calculating voltage across each component

Parallel Circuit Components are connected side by side There is more than one path for the current to flow around Components - on or off at the same or different times

Parallel Circuit Current is shared between the parallel paths Components of equal resistance = equal current A1 = Current in circuit A2 = A3 A1 = A2 + A3

Parallel Circuit Current is shared between the parallel paths Components of unequal resistance = unequal current A1 = Current in circuit A2 ≠ A3 A1 = A2 + A3

Parallel Circuit The voltage across each path = applied voltage R1 = R2

Parallel Circuit The voltage across each path = applied voltage R1 ≠ R2