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Diodes
Intermediate
Components that conduct in one direction.
A diode conducts in one direction (forward biased, above about 0.7 V for silicon) and blocks in the other. LEDs emit light when forward biased.
A diode in series with 5 V and 1 kΩ passes 4.3 mA.
Reverse breakdown can destroy it.
In more detail
A diode allows current to flow in only one direction, with low resistance in forward bias and high resistance in reverse bias. It is made from a junction of p-type and n-type semiconductors.
Real-world uses
- Diodes convert AC to DC in power supplies.
- LEDs are diodes that emit light when forward biased.
- Diodes in phone chargers allow current to flow in only one direction, protecting circuits from reversed batteries.
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Frequently asked questions
What is forward bias?
Connecting the positive side of the supply to the p-type side, letting current flow.
Do diodes have a threshold voltage?
Yes, silicon diodes conduct after about 0.6 to 0.7 volts.
Why does a diode need a forward voltage?
Its internal barrier must be overcome before current flows, which is about 0.7 V for a silicon diode.
Related topics in Current Electricity & Circuits
Time constant · Current in RC circuit · Capacitor networks · Rectifier circuits · Transistor as a switch and amplifier · Logic gates