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ELECTRICITY. Electricity per person per year = 22 trillion kWh / 7 billion = 3000 kWh (United States = 14,000 kWh). Originally, Electric Utilities Vertically Integrated Regional monopolies, highly regulated This ended in 1978 with PURPA (Public Utility Regulatory Policies Act)
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Electricity per person per year = 22 trillion kWh / 7 billion = 3000 kWh (United States = 14,000 kWh)
Originally, Electric Utilities Vertically Integrated • Regional monopolies, highly regulated • This ended in 1978 with PURPA (Public Utility Regulatory Policies Act) • Divided energy industry into Generation, Transmission, and Distribution • Opened the door to independent power producers
Originally, Electric Utilities Vertically Integrated • Regional monopolies, highly regulated • This ended in 1978 with PURPA (Public Utility Regulatory Policies Act) • Divided energy industry into Generation, Transmission, and Distribution • Opened the door to independent power producers • Many states encourage transition to renewable energy sources through Renewable Energy Portfolio Standards (RPS) Example: 10-20% of energy must come from renewable sources by a certain date
What is electricity? Flow of electrons
Atomic Models What are the 4 forces of the universe? Gravity Strong Nuclear Force Weak Nuclear Force Electromagnetism
Suppose I push against the wall…..what force am I using? Electromagnetism
Suppose I push against the wall…..what force am I using? Electromagnetism Can I ever actually touch the wall?
Suppose I push against the wall…..what force am I using? Electromagnetism Can I ever actually touch the wall? No!
How do batteries work? (Anode) (Cathode)
What is the current in the circuit? V = I R (Voltage = Current x Resistance) I = 8 amps
Appliances in Series: If V = 120 volts and R1 and R2 are both 5 ohm, what is the current in the circuit?
Appliances in Series: If V = 120 volts and R1 and R2 are both 5 ohm, what is the current in the circuit? V = I R 120 = I x 10 I = 12 amps
Appliances in Series: • If V = 120 volts and R1 and R2 are both 5 ohm, what is the current in the circuit? • V = I R • 120 = I x 10 • I = 12 amps • What happens to the voltage around the circuit?
Appliances in Series: • If V = 120 volts and R1 and R2 are both 5 ohm, what is the current in the circuit? • V = I R • 120 = I x 10 • I = 12 amps • What happens to the voltage around the circuit? • It drops in stages
Appliances in Series: What happens to the current if you keep adding resistors?
Appliances in Series: • What happens to the current if you keep adding resistors? • V = I R • 120 = I x (5+5+5+5) • I = 6 amps • The current drops
Appliances in Parallel: If V = 120 volts and R1 and R2 are both 5 ohm, what is the current in the circuit?
Appliances in Parallel: • If V = 120 volts and R1 and R2 are both 5 ohm, what is the current in the circuit? • 1 / Rtot = 1/5 + 1/5 • 1/Rtot = 2/5 • Rtot = 2.5 • V = I R • 120 = I x 2.5 • I = 48 amps
Appliances in Parallel: • If V = 120 volts and R1 and R2 are both 5 ohm, what is the current in the circuit? • 1 / Rtot = 1/5 + 1/5 • 1/Rtot = 2/5 • Rtot = 2.5 • V = I R • 120 = I x 2.5 • I = 48 amps • What happens to the voltage across them?
Appliances in Parallel: • If V = 120 volts and R1 and R2 are both 5 ohm, what is the current in the circuit? • 1 / Rtot = 1/5 + 1/5 • 1/Rtot = 2/5 • Rtot = 2.5 • V = I R • 120 = I x 2.5 • I = 48 amps • What happens to the voltage across them? • It is the same = 120 V
Appliances in Parallel: What happens to the current if you keep adding resistors?
Appliances in Parallel: • What happens to the current if you keep adding resistors? • 1 / Rtot = 1/5+1/5+1/5+1/5 • 1/Rtot = 4/5 • Rtot = 1.25 • V = I R • 120 = I x 1.25 • I = 96 amps • It increases
Why do you want Christmas lights to be in parallel, not series?
Why do you want Christmas lights to be in parallel, not series? Because if one fails, the whole circuit doesn’t stop
Why do you want Christmas lights to be in parallel, not series? Because if one fails, the whole circuit doesn’t stop Why might this still be a problem?
Why do you want Christmas lights to be in parallel, not series? Because if one fails, the whole circuit doesn’t stop Why might this still be a problem? Power delivered = volts x current P = VI P = (IR)I P = I2R The power increases with the square of the current, and current is greater for parallel circuits you are more likely to blow a fuse.
An Electric Current in a wire generates an electric field rotating around it!