Question

Eddy currents are not used in the applicalion of

• A. induction fumace
• B. thermal generators
• C. electomagnetic damping
• D. electric power meters
• E. magnetic braking in tains

Answer 1

The Correct Option is D

Applications of Eddy Currents 

We want to identify which application *does not* utilize eddy currents.

Step 1: Understanding Eddy Currents

Eddy currents are circulating currents induced within a conductor when it is exposed to a changing magnetic field. They are used in various applications due to their heating effects, damping properties, or force generation.

Step 2: Applications Utilizing Eddy Currents

• Induction Furnace: Eddy currents are used to heat and melt metals. A strong alternating magnetic field induces eddy currents in the metal, causing it to heat up due to resistance.
• Electromagnetic Damping: Eddy currents are used to provide damping forces, such as in galvanometers and other sensitive instruments.
• Electric Power Meters: Some types of electric power meters (especially older designs) use eddy currents to measure the power consumption.
• Magnetic Braking in Trains: Eddy currents are used to create braking forces in some trains. A magnetic field is applied to the rails, inducing eddy currents in the wheels, which create a force opposing the motion.

Step 3: Thermal Generators

Thermal generators (also known as thermoelectric generators) directly convert heat into electrical energy, relying on the Seebeck effect (a thermoelectric effect) instead of magnetic induction and eddy currents.

Conclusion

Eddy currents are *not* used in the application of thermal generators. Thermal generators rely on the Seebeck effect. The fact that you are trying to heat metal and transform it to electricity is a consequence of having current. The induction coil is there to generate Eddy currents and not to create electrical energy. This is the key difference to correctly highlight that thermal generators are separate to eddy current technology, whereas an electrical power meter makes use of Eddy Currents.