What does electrical isolation accomplish between circuits from different power domains?

• A. It prevents electrical interaction between circuits of different power domains.
• B. It increases signal bandwidth.
• C. It eliminates the need for a common ground reference.
• D. It converts DC to AC.

Answer: (A)

Electrical isolation creates a barrier that stops current and voltage from one power domain from affecting another. When circuits run from different supplies or grounds, direct connections can let noise, faults, or ground loops travel between them. By using an isolation barrier—such as an optocoupler, transformer, or capacitive/inductive isolator—the signal is transferred without a direct conductive path. This keeps the domains electrically separate while still allowing control or sensing signals to pass, protecting equipment and reducing interference. It doesn’t inherently increase bandwidth, and it doesn’t remove the need for a reference on each side or convert DC to AC.