AD - Why do I get this spark when I unplug my hair dryer?

Splitting a big voltage drop across multiple conversion stages and switching much faster lets designers use much smaller inductors because each coil only has to absorb a smaller amount of energy per cycle.

Higher-voltage or higher-power conversion needs larger inductors because each inductor must store and handle more energy per switching cycle, and greater energy capacity requires bigger physical size.

Inductors smooth choppy outputs by storing energy in their magnetic field when current rises and releasing it when current falls, which acts like a shock absorber to turn pulses into steadier DC.

Switch-mode chargers produce pulsed electricity because transistors switch the current on and off hundreds of thousands of times per second, and those pulses are then converted into lower-voltage DC.

That induced voltage can produce a visible spark because it can rise high enough to ionize the air gap between plug and socket, which lets current jump across where it otherwise could not.

Unplugging a running appliance can create a high-voltage spike because the coil’s magnetic field collapses when current is cut and that changing field induces a voltage that tries to keep the current flowing.