Comprehensive Study Notes on Magnetism, Electromagnetism, and Inductive Technology

Magnetic technology on consumer cards has evolved significantly from the traditional magnetic strip found on older debit and credit cards.
Contemporary cards primarily use a gold chip (EMV) and "tap" technology for transactions.
This transition was driven by the need for increased security, often referred to as "two-factor identification," requiring both a tap (or chip insertion) and a PIN (Personal Identification Number).
The move away from magnetic strips was largely due to the rise of "card skimming," where criminals use fake card readers to steal data.
Pickpocketing was historically common at large sporting events, concerts, or in big cities, where a thief would bump into someone to steal a wallet or purse. Today, digital pickpocketing allows thieves to scan card information just by walking past someone with a scanner.
The instructor shares a personal anecdote of having a card skimmed at a BP gas station "up at the ground about, like, Culver's" approximately $5$ years ago. Before he reached the aircraft hangar on the other side of Indianapolis where he worked, Chase Bank called to report fraudulent charges appearing in Texas while the card was identified as being from Indianapolis.
RFID (Radio Frequency Identification) protection is now included in many small wallets or phone-attached card holders. This protection act as a "walking light," blocking the radio frequency scanners from accessing card data.
Payment Security Hierarchy: - Cash: Viewed by some as secure, but risky because if dropped, it is rarely returned (e.g., finding a $\$50$ bill on a bus). - Checks: Mentioned as a traditional method but not preferred in the current context. - Apple Pay, Google Pay, and PayPal: These are described as the most secure ways to pay. Apple Pay is specifically highlighted as being extremely difficult to "crack," even for those portrayed in crime movies.
Online Shopping Safety: - Credit cards are generally safer than debit cards for online purchases because they offer more protection. - Using a debit card is dangerous because it is linked directly to your own money. If a debit card is skimmed, it can take $1$ to $2$ months to recover the funds. During that time, the user might be unable to pay essential bills, such as electric, because utility companies often do not accept "my card was skimmed" as an excuse for late payment. - Credit card companies can kill the compromised card, send a new one, and remove the charges without it counting against the user's personal bank balance.

Home Security Systems and Magnetic Sensors

Popular home alarm brands include ADP, SimpliSafe, and Ring.
These systems utilize two magnetic sensors (often placed on windows or doors).
Mechanics of the alarm sensor: - A magnetic field between the two sensors pulls a switch open on the receiver unit. - When a window is moved up or a door is opened, the magnetic fields no longer influence each other. - The little switch then closes the circuit. - A signal is sent to the base station identifying which specific entry point (e.g., "front door" or "living room window") is open. - The system performs "math": if the alarm is on and a sensor is triggered, it sounds the siren (the "bloop bloop" sound).

History and Properties of Magnets

The term "magnet" originates from a region called Magnesia, where Greeks discovered metallic rocks thousands of years ago.
The rocks were found to be ferromagnetic, composed primarily of Iron (labeled on the periodic table as $Fe$ ).
Early observers noticed that when these rocks were hung from a string, they would always align with the Earth's magnetic field and point North.
The Earth's magnetic field is generated by the molten core which is in constant motion.
All magnets possess both a North and a South pole.

The Magnetosphere and Atmospheric Effects

The magnetosphere is a magnetic field surrounding Earth that provides a vital protective shield.
It protects the planet from "solar wind" and "solar rays" (solar radiation).
Massive solar flares blast radiation through space. When this hits the Earth's magnetic field, it "dents" the field and deflects the radiation around the planet.
These "dents" can disrupt electromagnetic communications on Earth.
Modern weather forecasts now include indices for electromagnetic storms, such as $G2$ or $G4$ storms.
Auroras (The Lights): - High electromagnetic activity results in the Aurora Borealis (Northern Lights) and Aurora Australis (Southern Lights). - These occur because particles get caught in the atmosphere and are pulled toward the poles, where the magnetic field is strongest. The particles then burn up like meteorites. - Aurora Borealis Visibility: Alaska, Canada, the northern United States, Norway, Finland, Sweden, and Northern Russia. - Aurora Australis Visibility: Harder to witness as Antarctica is mostly inhabited by "penguins and dirty scientists." It might be seen in New Zealand or Southern Argentina.
Geographic Note: Antarctica contains the largest vertical free-fall cliff on the planet, measuring about $4,000$ or $5,000$ feet, currently buried in ice. LiDAR (Light Image Detecting and Ranging) scans reveal massive mountain ranges beneath the Antarctic ice.

Electromagnetism Principles

In the $1800$ s, scientists noticed that compasses were affected by the electric charge in the air after heavy lightning storms.
Hans Christian Ørsted (a science teacher) discovered the relationship between electricity and magnetism. He observed that a compass sitting near a circuit would point one way when the power was on and return to its original position when the power was off.
Core Principle: A current moving through a wire generates a magnetic field around it.
Visualizing the Field: An experiment involves placing iron shavings on a piece of cardboard around a wire. When electricity flows, the shavings align in concentric circles. If the current moves upward, the magnetic field curls counter-clockwise.
Electromagnets are magnets that can be turned on and off.
Coiling the wire creates a stronger magnetic field inside the coil. If an iron nail is placed inside the coil, it becomes a "super magnet" known as a solenoid or electromagnet.

Applications of Electromagnetism

Internal Combustion Vehicles: Use a solenoid to start the car. Because a battery only produces limited electricity, the solenoid magnifies the electrical spark to engage the starter.
Industrial Junkyards: Large electromagnetic plates (like those used at "Doobie's Scrap Metal") are attached to cranes to pick up shredded metal. When the electricity kicks on (often with a buzzing sound), the metal sticks to the plate. It is then moved over a train car and dropped by turning off the current. The speaker mentions "Butt Brothers" in relation to these crane operations.
Home Appliances: Hair dryers and vacuum cleaners use electric motors based on electromagnetism.
Speaker Technology: - Electricity from an amplifier flows to a coil (solenoid) on the back of the speaker. - Every speaker has a permanent magnet; larger speakers, like subwoofers, have larger magnets. - The interaction (attraction or repulsion) between the electromagnetic field of the coil and the permanent magnet causes the speaker cone to move in and out. - This movement creates rarefaction and compression in the air, resulting in sound waves.

Traffic Sensors and Inductive Loops

Octagonal shapes cut into the concrete at stoplights are inductive sensors.
They consist of an electrical circuit buried in the pavement.
When a car (which has its own electrical flow and magnetic field) stop over the cut, it influences the electricity in the road circuit through induction.
This signal is sent to a box on a telephone pole that controls the light timing.
Police officers can manually override these boxes to manage traffic (e.g., allowing school buses to leave).
Civil Engineers: One responsibility of civil engineers is performing traffic flow studies and timing stoplights. However, power outages and other factors can cause lights to become out of sync over time.
Example: At $116$ th Street by the Dennis and Kroger, the light is often red even if it is only $100$ feet away from previous lights.
Traffic Comparison: Olio Road (OA) is one of the busiest in the city. A light might be timed for $4$ minutes of green for Olio Road and only $1$ minute for $126$ th Street.
Late-Night Sensors: At $11:30$ PM, if a car sits at a red light on a side road, the inductive sensor tells the box that a car is and starts a timer. If no traffic passes on the main road for $30$ seconds, it flips the light to green.

Generators and Power Plants

Induction: Moving a magnet around a wire causes electricity to flow in that wire.
A generator converts mechanical energy into electrical energy. In contrast, a motor converts electrical energy into mechanical energy.
The central component of a power plant is a turbine.
Methods of spinning the turbine: - Windmills: Wind blows fan blades to spin gears. If the speed exceeds $90$ RPM (revolutions per minute), the blades go flat to prevent gear damage and overheating. - Hydroelectric: Water flows through a dam and across the turbine. - Coal burning: Burning coal heats water into steam, which is pumped through tubes to spin the turbine. - Nuclear: Nuclear reactions heat water into steam for the same purpose. - Geothermal: Uses temperature differences between the earth and the surface; it is rare and expensive.

Questions & Discussion

Question/Topic: Canvas Ransomware. - Discussion: The speaker mentions that Canvas was allegedly shut down and held for ransom the previous week. It is unclear if a ransom was paid, but the speaker notes that colleges will typically just push finals back rather than cancel them.
Question/Topic: Windmills between Purdue and Merrillville. - Discussion: There are approximately " $75,000,000,000$ " windmills in that region. When asked why some are turned off, the speaker explains they likely caught too much wind and were shut off to prevent overheating.
Unsubmitted Project: A student discusses a missed project submission despite having it completed. The speaker mentions having sent an email regarding the presentation and the reason for the delay.