Important Concepts

  • There are two types of electrical current flow; direct current (DC) and alternating current (AC).
  • DC flows in one direction only and is the primary type of current used in logic and control circuits.
  • AC alternates in polarity, flowing back and forth, and is the main type of current found in household electrical mains.
  • AC is the typical current used to power appliances, and is often converted to DC within an appliance to power the logic circuit boards.
  • Mapping the polarity of household AC over time reveals a sine wave, but it may also have other waveforms.
  • AC is described by its period (cycle time), frequency (cycles per second, measured in hertz (hz)), and amplitude (magnitude of waveform measured in volts).

Part 4: Resistance and Ohm’s Law


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