The Physics
Faraday's Law and Lenz's Law come alive with interactive simulations showing exactly how changing magnetic fields create opposing forces.
Interactive
Formulas
โก Interactive Physics Experience
Discover Eddy Currents
The invisible electromagnetic force revolutionizing transportation, from roller coasters to 600 km/h levitating trains
4
Interactive Labs
603
km/h Top Speed
0
Contact Friction
N
S
Moving Magnet
Eddy Currents
โต Braking Force
Explore the Science
Roller Coasters
Experience frictionless braking systems that stop multi-ton coaster trains smoothly without ever touching them.
Simulation
Safety
Maglev Trains
Levitate and propel trains to 603 km/h using nothing but magnets and the power of eddy currents.
Levitation
Speed
Virtual Lab
Conduct 5 hands-on experiments: pendulum damping, tube drops, induction heating, and more with real-time physics.
5 Experiments
Quiz
The Physics
Understanding electromagnetic induction and Lenz's Law
1
Faraday's Law
ฮต = -N
dฮฆ
dt
A changing magnetic flux through a conductor induces an electromotive force (EMF). The faster the change, the stronger the induced current.
ฮตinduced EMF
Nnumber of turns
ฮฆmagnetic flux
ttime
2
Lenz's Law
F = -k ยท v
The induced current flows in a direction that opposes the change producing it. This is the fundamental principle behind magnetic braking!
โ Motion
โ Opposition
Live Simulation
Ready
Factors Affecting Eddy Currents
Conductivity (ฯ)
Higher conductivity allows larger current loops, creating stronger opposing fields.
Magnetic Field (B)
Weak B
โ
Strong B
Stronger magnets induce larger EMF, resulting in stronger eddy currents and braking.
Velocity (v)
Slow
Fast
dฮฆ/dt is proportional to velocity. Faster motion = faster flux change = stronger currents.
Geometry
Solid
Slotted
Slits interrupt current paths. This is why brake discs have holes - to reduce eddy current drag!
Roller Coasters
Frictionless braking systems that stop multi-ton trains
How It Works
1
The coaster enters the brake zone at high speed
2
Copper fins on the car pass between powerful magnets
3
Changing magnetic field induces eddy currents in copper
4
Lenz's Law: Eddy currents create opposing magnetic field
5
Magnetic drag smoothly decelerates the train
Advantages
-
Fail-Safe Works without power - passive safety
-
Silent No friction = no screeching noise
-
Cool No heat buildup from friction
-
Durable No wear and tear - lasts decades
-
Progressive Braking force increases with speed
Real World Applications
๐ผ
Tower of Terror
Disney's drop towers use eddy current braking for smooth, controlled stops at the end of the freefall experience.
Drop Tower๐ข
Intamin Mega Coasters
High-speed coasters like Kingda Ka use magnetic fin brakes for reliable, maintenance-free stopping.
Speed Record๐ฆ
B&M Dive Machines
Hold and drop coasters use eddy current brakes to precisely control train speed after the vertical drop.
Precision ControlMaglev Trains
Levitating at 603 km/h using electromagnetic suspension
N
โ
โป
โ
Electrodynamic Suspension (EDS)
Superconducting magnets on the train move past conductive coils in the guideway. This motion induces eddy currents that create an opposing magnetic field, pushing the train upward.
- Levitation Gap: 100mm (4 inches)
- Lift Force: Proportional to speed
- Minimum Speed: ~150 km/h for full levitation
A+
B-
C+
A-
B+
โ
Linear Synchronous Motor (LSM)
The guideway contains electromagnets arranged in phases (A, B, C). By alternating the current, a traveling magnetic wave is created that pulls the train forward.
- Max Speed: 603 km/h (Japan L0 Series)
- Acceleration: Smooth and precise
- Efficiency: 90%+ at cruising speed
Maglev vs Traditional Rail
Feature
Maglev
Traditional
Top Speed
603 km/h
~320 km/h
Contact / Friction
Zero
Wheel-rail contact
Noise Level
Very Low
Moderate-High
Maintenance
Low
High (wheels, rails)
Gradient Capability
10%
~4%
Infrastructure Cost
Higher
Lower
More Applications
Eddy currents are everywhere - from your kitchen to particle accelerators
Induction Cooking
Rapidly alternating magnetic fields create intense eddy currents in the pot, heating it directly. The cooktop stays cool!
90%
Energy efficient
Metal Detectors
Eddy currents induced in metallic objects create their own magnetic field, which is detected by the sensor coil.
~1m
Detection range
Induction Heating
Used for metal hardening, brazing, and melting. Eddy currents heat the surface while the core stays cool.
>1000ยฐC
In seconds
Eddy Current Testing
Non-destructive testing for cracks and flaws in metals. Used in aerospace and manufacturing quality control.
ฮผm
Defect sensitivity
Gym Equipment
Some exercise bikes and rowing machines use eddy current resistance - smooth, silent, and infinitely adjustable.
โ
Resistance levels
Particle Accelerators
Used to steer and focus particle beams. The eddy current kickers can switch beam paths in nanoseconds.
ns
Switching time
Virtual Lab
Conduct experiments and discover the physics yourself
Exp 01
Magnetic Pendulum
The pendulum magnet swings over a conductive sheet. Eddy currents create magnetic drag that slows the swing. Adding slits interrupts current paths, reducing the effect.
Exp 02
The Tube Drop Race
Drop magnets through different tubes. Copper creates strong eddy currents that dramatically slow the fall. PVC (an insulator) has no effect - the magnet falls at nearly free-fall speed.
Exp 03
Induction Heating
Material:
Iron
High-frequency AC in the coil creates rapidly changing magnetic fields. Eddy currents in the metal convert electrical energy to heat. Higher frequency = more heating. This is how induction cooktops work!
Exp 04
Conductivity Comparison
Copper (Best)
Aluminum
Steel
See how different materials respond to the same magnetic field. Higher conductivity = stronger eddy currents = more braking effect.
Exp 05
Magnetic Damping
A weight falls through a copper tube. With the magnet active, eddy currents slow the fall. Turn off the magnet and watch it fall freely!
๐ฏ Knowledge Check
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