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Questions on Characteristic Curves - the silicon semiconductor diode

Q1.

(a) Sketch the characteristic of a silicon semiconductor diode for forward bias and reverse bias. Indicate approximate values on the voltage axis.

forward bias: zero current at origin rising gradually sharp increase at just before 0.7 V

reverse bias: zero at origin then slightly less than zero current

(4 marks)

(b) Describe, with reference to the characteristic you have drawn, how the resistance of the diode changes with the voltage across the diode.

forward bias: The diaode has a high resistance if the potential difference across it is less than 0.7 V this is why only a small current passes through it.

At 0.7 V resistance decreases rapidly this results in a rapidly increasing current.

reverse bias: The diode has a very high resistance therefore very little current is conducted through it.

(3 marks)

(Total 7 marks)