Final answer:
Magnetic braking in roller coasters is based on the creation of eddy currents when the conductive parts of the train interact with a magnetic field, generating a braking force that slows the train down smoothly and reliably, although additional brakes are needed to bring it to a complete stop.
Step-by-step explanation:
Principle Behind Magnetic Braking in Roller Coasters
The principle behind magnetic braking in roller coasters involves the generation of eddy currents. These currents are created when a conducting plate, often made from a material like copper, passes through the magnetic field of permanent rare-earth magnets fixed on the track. The interaction of the moving conductive material and the magnetic field induces circular currents, known as eddy currents, within the conductor. According to Lenz's Law, the induced eddy currents generate their own magnetic fields, which oppose the motion that created them. This opposition creates a braking force against the movement of the roller coaster train, effectively slowing it down without any physical contact between the brake and the train.
The use of magnetic brakes is advantageous as these systems are not affected by weather conditions such as rain, and provide smoother deceleration compared to friction-based braking systems. However, the braking force provided by eddy currents diminishes as the vehicle's speed decreases, which means that magnetic braking alone cannot bring the train to a complete stop. Additional braking systems are required to halt the roller coaster completely. Roller coasters typically employ powerful rare-earth magnets, like neodymium magnets, to achieve efficient magnetic braking.