What Is Polarity?
Polarity means a component has a positive (+) and negative (−) direction. Polarized components work only when connected the right way round; connecting them backwards leads to non-operation or damage.
What Is Polarity?
Some components don't have two identical ends; one must connect to the positive side, the other to the negative. This direction comes from the component's internal structure (e.g. a semiconductor junction).
Polarized Components
| Component | Polarity marking |
|---|---|
| Diode | Band on the body = cathode (−) |
| LED | Long leg = anode (+) |
| Electrolytic capacitor | Striped side = negative (−) |
| Battery | + and − terminals |
How Do We Tell the Polarity?
The markings differ by component: on an LED the long leg is positive; on a diode the band marks the cathode; on an electrolytic capacitor the stripe marks the negative. On ICs, a dot/notch marks pin 1 (package types).
The Result of Connecting Backwards
Installing a polarized component backwards causes results like an LED not lighting, a diode not conducting, or an electrolytic capacitor heating up and bursting. Non-polarized components (fixed resistor, ceramic capacitor) can be installed either way.
Common Mistakes
- Installing an LED backwards: it won't light; make sure the long leg goes to positive.
- Installing an electrolytic capacitor backwards: it's dangerous — it can heat up and burst.
- Missing pin 1 on an IC: if the notch/dot direction is wrong, the chip burns.
Frequently Asked Questions
Does every component have a polarity?+
Can I tell the polarity from the schematic?+
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