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Electricity and Magnetism, download, download-1, download, download-2,…
Electricity and Magnetism
series and parallel circuits
series circuit
One path for current
Current is the same everywhere
Rtotal = R1 + R2
parallel circuits
Multiple paths for current
Voltage is the same across each branch
1/Rtotal = 1/R1 + 1/R2
Electrical Safety
Fuses and circuit breaker
Protect against overcurrent
Break the circuit if too much current flows
ground fault circuit interrupter
Shuts off power if leakage current is detected
Often used in bathrooms and kitchens
proper grounding
Directs stray current safely into the earth
Electrical Power and Energy
Electrical power formula
P=VI (power = voltage x current)
energy usage
E=Pt (energy = power x time)
energy units
joules (j), kilowatt-hours (kWh)
cost of energy
cost = energy (kWh) x rate
electrical circuits
components
Resistors, power sources, switches, bulbs
circuit diagrams
Use standard symbols to represent components
closed vs. open circuits
Current flows only in a closed circuit
short circuit
Dangerous path of low resistance
electric currents
Flow of electric charge (electrons)
direction
Conventional current flows from + to –
measured by Ammeter (in series)
voltage
Energy per charge that drives current
unit
volt (V)
sources
Batteries, generators
electrical resistance
Opposition to current flow
unit
Ohm Ω
depends on the material, length and thickness of the wire, and temperature
symbol
Resistor: zigzag line
Ohm's Law
V=IR (Voltage = Current × Resistance)
Used to Calculate any one of the three variables if the other two are known
magnetism
magnetic fields
Created by moving charges or magnets
right-hand rule
Determines direction of magnetic field or force
Applications
Motors, generators, transformers
Electromagnetism
Link between electricity and magnetism
Basis of modern electrical technology
