Diode Flashcards
What does a diode do?
Allows current to flow in only 1 particular direction
What is a diode made of?
Made from a semiconductor
What is one property of the light emitted by LED’s
They emit light which has a single specific wavelength
What are 3 properties of a an LED
LED’s dont get hot so much more efficient as they draw much less power
Turns on intstantly
And they also last much longer
Why is a LED sometimes used in a circuit
They are used as simple indicators, to show direction of current through a specific part of circuit.
They light up when current is in them, showing that this part of circuit is live.
What are the 3 IV characteristics of a diode?
- It does not obey ohm’s law as PD is not directly proportional to the current
- The resistance of diode is not constant
- The behaviour of diode depends on the polarity
Why is there no current when PD is negative in a diode?
Why is there current when PD is positive in diode?
current is in reverse direction so diode does not conduct
As current flowing in the right direction
How much resistance is there at the negative side of the diode’s IV graph?
And why.
There is very high resistance, infinite for practical purposes.
Because it wont allow current to flow through as the polarity of cell is opposite.
What type of lights are used for rear lights for cars now.
And how does this type of Light work.
Lights are made up of arrays of LED’S.
Works by transferring electrical energy directly into light.
What value of V does resistance start to gradually drop in a silicon diode
0.7V
What happens to resistance when a very small change in PD occurs above the PD threshold of the silicon diode.
Resistance drops sharply for small increase in PD
Very little resistance.
