Key Points

• Transformers are essential for stepping up or stepping down AC voltage using electromagnetic induction.

• The relationship between the primary and secondary voltages is determined by the number of turns in the coils.

• Transformers cannot operate on DC due to the lack of changing magnetic flux.

Understanding Transformers

Transformers are devices that can either step up or step down voltage. They consist of two coils: the primary coil connected to the AC supply and the secondary coil connected to the device being powered. The principle behind their operation is electromagnetic induction, where a changing current in the primary coil induces an electromotive force (emf) in the secondary coil due to fluctuating magnetic fields explained at 100 seconds.

How Transformers Work

When AC voltage is applied to the primary coil, it generates a fluctuating magnetic field. This changing magnetic field induces an emf in the secondary coil, allowing current to flow and power devices like microwaves discussed at 350 seconds. The voltage in the secondary coil can be calculated based on the ratio of the number of turns in the primary and secondary coils explained at 321 seconds.

Applications of Transformers

• Step-Up Transformers: Increase voltage for high-power devices, such as microwaves mentioned at 348 seconds.
• Step-Down Transformers: Decrease voltage for low-power devices, like mobile phones discussed at 394 seconds.

Key Takeaways

Transformers are crucial for efficient power transmission and device operation. They work only with AC due to the need for changing magnetic flux, which is absent in DC systems explained at 469 seconds. To ensure effective operation, a ferromagnetic core is used to maintain consistent magnetic flux between the coils discussed at 486 seconds.