What devices have polarity?

• A. Resistors and inductors
• B. Transformers and capacitors
• C. Electrolytic capacitors and diodes
• D. Switches and relays

Answer: (C)

Polarity matters for components whose behavior depends on the direction of voltage or current. Electrolytic capacitors are polarized; one lead must be positive and the other negative, and reversing them can damage the capacitor or cause it to fail. Diodes are also polarized; current can flow only from the anode to the cathode, so wiring them backward prevents conduction and can destroy the diode. These two types require a specific orientation to function safely, which is why they are described as having polarity.

Other common components don’t rely on a fixed orientation. Resistors and inductors work the same no matter which end is connected. Transformers have a phase relationship indicated by dot conventions rather than a simple positive/negative polarity. Many capacitors (like film or ceramic types) are non-polar and tolerate either orientation. Switches and relays are about making or breaking a connection and typically don’t depend on polarity for operation, though coils with protective diodes add polarity considerations in that context.