Semiconductors

Question 1

A silicon diode measures a low value
of resistance with the meter leads in
both positions. The trouble, if any, is

Answer 1

the diode is internally shorted.

Question 2

Single-element semiconductors are
characterized by atoms with ____
valence electrons.

Answer 2

4

Question 3

Under normal conditions a diode
conducts current when it is

Answer 3

forward-biased.

Question 4

A diode conducts when it is forward-
biased, and the anode is connected to
the ________ through a limiting resistor.

Answer 4

positive supply

Question 5

As the forward current through a
silicon diode increases, the internal
resistance

Answer 5

decreases.

Question 6

The movement of free electrons in a
conductor is called

Answer 6

current.

Question 7

For a forward-biased diode, the barrier
potential ________ as temperature
increase

Answer 7

decreases

Question 8

The wide end arrow on a schematic
indicates the ________ of a diode.

Answer 8

anode

Question 9

An n-type semiconductor material

Answer 9

has pentavalent impurity
atoms added.

Question 10

For a forward-biased diode, as
temperature is ________, the forward
current ________ for a given value of
forward voltage.

Answer 10

increased, increases

Question 11

Which statement best describes
an insulator?

Answer 11

A material with few free
electrons.

Question 12

Effectively, how many valence
electrons are there in each atom within a silicon crystal?

Answer 12

8

Question 13

The boundary between p-type
material and n-type material is called

Answer 13

a pn junction.

Question 14

You have an unknown type of diode
in a circuit. You measure the voltage
across it and find it to be 0.3 V. The
diode might be

Answer 14

a germanium diode.

Question 15

An ideal diode presents a(n)
________ when reversed-biased and a(n)
________ when forward-biased.

Answer 15

open, short

Question 16

A reverse-biased diode has the
________ connected to the positive side
of the source, and the ________
connected to the negative side of the
source.

Answer 16

cathode, anode

Question 17

What types of impurity atoms are
added to increase the number of
conduction-band electrons in intrinsic
silicon?

Answer 17

pentavalent

Question 18

Reverse breakdown is a condition in
which a diode

Answer 18

is subjected to a large reverse
voltage.

Question 19

There is a small amount of current
across the barrier of a reverse-biased
diode. This current is called

Answer 19

reverse leakage current.

Question 20

As the forward current through a
silicon diode increases, the voltage
across the diode

Answer 20

is relatively constant.

Question 21

Doping of a semiconductor material
means

Answer 21

that impurities are added to
decrease the resistance of
the material.

Question 22

The forward voltage across a
conducting silicon diode is about

Answer 22

0.7 V.

Question 23

The most common type of diode
failure is a(n) ________.

Answer 23

open

Question 24

What occurs when a conduction-
band electron loses energy and falls
back into a hole in the valence band?

Answer 24

recombination

Question 25

The maximum number of electrons in each shell of an atom is

Answer 25

2n2 where n is the number of the shell.

Question 26

A silicon diode is forward-biased. You measure the voltage to ground from the anode at ________, and the voltage from the cathode to ground at ________.

Answer 26

2.3 V, 1.6 V

Question 27

The term bias in electronics usually means

Answer 27

the value of dc voltages for the device to operate properly.