1. When a silicon diode's forward current increases, its internal resistance decreases. Atoms in a silicon crystal each have four valence electrons. Pentavalent impurity atoms are added to intrinsic silicon to increase the number of conduction band electrons. When a conduction band electron loses energy and falls into a hole in the valence band, recombination occurs. Materials that conduct electricity under certain circumstances are called semiconductors. 2. A diode conducts when forward biased with the anode connected to the positive supply through a limiting resistor. The wide end arrow indicates the anode. As temperature increases, forward current increases for a given forward voltage. A reverse biased diode has the cathode connected to the positive source and the

1. Worksheet
Question 1
One word answer
i. What happens to the internal resistance as the forward current through a silicon diode
increases? (Decreases)
ii. Effectively, how many valence electrons are there in each atom within a silicon
crystal?(Four)
iii. What types of impurity atoms are added to increase the number of conduction-band
electrons in intrinsic silicon?(Pentavalent)
iv. What occurs when a conduction-band electron loses energy and falls back into a hole in the
valence band?(Recombination)
v. What are materials that conduct electricity under certain circumstances called?
(Semiconductors)
(5)
Question 2
Fill in the following sentences:-
i. A diode conducts when it is forward-biased, and the anode is connected to the ________
through a limiting resistor.(Positive supply)
ii. The wide end arrow on a schematic indicates the ________ of a diode.(Anode)
iii. For a forward-biased diode, as temperature is ________, the forward current ________ for a
given value of forward voltage.(increased, increases)
iv. A reverse-biased diode has the ________ connected to the positive side of the source, and
the ________ connected to the negative side of the source.(Cathode, Anode)
v. As the forward current through a silicon diode increases, the voltage across the diode
is____________________. (constant)
vi. The most common type of diode failure is a(n) ________. (Open)
(8)
Question 3
Describe how the PN-Junction Diode will conduct when it is forward biased.
(12)
Total: 25