Physics Principles and Problems 2009

Chapter 29: Solid-State Electronics

Standardized Test Practice

1
The voltage across an LED is 1.5 V when it is in a circuit with 9.0-V battery and a 225-Ω resistor. What is the current through the resistor?
A)6.7 mA
B)33 mA
C)40 mA
D)47 mA
2
According to the band theory of solids, why is lead a good conductor?
A)There is a wide energy gap between the valence band and conduction band of lead.
B)The valence band of lead is empty and the conduction band is filled.
C)A great deal of energy is needed to move valence electrons of lead to the conduction band.
D)The conduction band of lead overlaps the valence band.
3
Which of the following elements has the correct number of valence electrons to be used as a dopant for an n-type semiconductor?
A)beryllium (Z = 4)
B)boron (Z = 5)
C)nitrogen (Z = 7)
D)aluminum (Z = 13)
4
The diagram shows a circuit connecting a diode, a 550-Ω resistor, and a power supply that forward-biases the diode. If the diode with a voltage drop of 0.7 V has a current of 0.015 A, what is the voltage of the power supply?

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A)7 V
B)8 V
C)9 V
D)10 V
5
When arsenic is used as a dopant to improve the conductivity of silicon (Si), each arsenic atom donates one electron. If there are 4.99 × 1022 Si atoms per cm3 and 1 in every million Si atoms is replaced by an arsenic atom, how many free electrons from arsenic are there in 1 cm3 of doped silicon?
A)4.99 × 1016
B)5.24 × 1016
C)6.78 × 1020
D)4.99 × 1022
6
How does a transistor affect voltage?
A)It causes voltage to decrease.
B)It reduces large voltage changes.
C)It does not affect voltage.
D)It amplifies small voltage changes.
7
What is the approximate energy gap between the valence band and conduction band of a semiconductor?
A)0 eV
B)1 eV
C)5 eV
D)10 eV
8
The diagram shows a series circuit with a battery, a resistor, and an LED. If the current is 15 mA, what is the resistance?

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  Need a Hint?
A)9.3 × 101 Ω
B)5.1 × 102 Ω
C)6.0 × 102 Ω
D)6.9 × 102 Ω
9
How do dopants increase the conductivity of semiconductors?
A)They add net charge to the semiconductor.
B)They increase the forbidden gap.
C)They make extra electrons or holes available.
D)They turn them into intrinsic semiconductors.
10
What is another name for an integrated circuit?
A)transistor
B)semiconductor
C)diode
D)microchip
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