Renñier A.
Salvador
BSECE 4-5
PROBLEM SET: Elex04 – Review of Electronic Devices and Components
1.
A semiconductor has a resistivity of 10⁻³ Ω·m. If the cross-sectional area of the
material is 1 cm² and the length is 1 m, what is the resistance of the material?
A) 10 Ω
B) 100 Ω
C) 1000 Ω
D) 10⁶ Ω
Answer: A
2.
A P-type semiconductor has a hole concentration of 10¹⁸ holes/m³. If the electron
mobility is 0.1 m²/V·s, what is the electrical conductivity of the material?
A) 0.1 S/m
B) 0.5 S/m
C) 1 S/m
D) 0.05 S/m
Answer: D
3.
In an intrinsic semiconductor, if the temperature is increased from 300 K to 350 K,
what happens to the conductivity?
A) It decreases
B) It remains constant
C) It increases
D) It becomes zero
Answer: C
4.
A P-N junction has a forward bias of 0.7 V applied to it. The current through the
junction is 10 mA. What is the resistance of the diode in this condition (assuming
ideal diode behavior)?
A) 0.07 Ω
B) 7 Ω
C) 70 Ω
D) 700 Ω
Answer: B
5.
In an N-type semiconductor, the majority charge carriers are:
A) Electrons
B) Holes
C) Ions
D) Protons
Answer: A
6.
If the energy band gap of a semiconductor is 1.1 eV, at what temperature will the
intrinsic carrier concentration increase by 100 times, assuming thermal excitation
is the primary mechanism for conduction?
A) 300 K
B) 600 K
C) 900 K
D) 1200 K
Answer: B
7.
If a semiconductor is doped with donor atoms, it becomes a:
A) P-type material
B) N-type material
C) Pure semiconductor
D) Conductive material
Answer: B
8.
The intrinsic carrier concentration of silicon at 300 K is 1.5 × 10¹⁶ carriers/m³. If
the temperature is increased to 400 K, the carrier concentration becomes
approximately 5 × 10²⁰ carriers/m³. What is the temperature dependence of the
carrier concentration?
A) Linear
B) Exponential
C) Logarithmic
D) Quadratic
Answer: B
9.
In a P-N junction, the built-in potential is 0.7 V at room temperature. If the
temperature is increased, the built-in potential:
A) Increases
B) Decreases
C) Stays the same
D) Becomes zero
Answer: B
10.
If the mobility of electrons in a semiconductor is 0.14 m²/V·s and the concentration
of electrons is 10¹⁸ electrons/m³, what is the conductivity of the semiconductor?
A) 1.4 S/m
B) 0.14 S/m
C) 14 S/m
D) 0.014 S/m
Answer: A
11.
A diode has a forward voltage drop of 0.7 V and a current of 5 mA. What is the
power dissipated by the diode?
A) 0.7 mW
B) 3.5 mW
C) 7 mW
D) 35 mW
Answer: B
12.
In a P-N junction diode, if the forward bias is increased, the current:
A) Decreases exponentially
B) Increases exponentially
C) Increases linearly
D) Remains constant
Answer: B
13.
What is the reverse breakdown voltage of a diode if the current through the diode
is 10 mA and the resistance in the reverse bias circuit is 1000 Ω?
A) 0.1 V
B) 1 V
C) 10 V
D) 100 V
Answer: C
14.
In a Zener diode, the Zener breakdown voltage is 5.1 V. If the diode is reverse
biased at 6 V, what will be the voltage across the diode?
A) 5.1 V
B) 6 V
C) 0 V
D) 10.1 V
Answer: A
15.
What is the ideal diode behavior when forward biased?
A) It behaves like a short circuit
B) It behaves like an open circuit
C) It allows current to flow with no resistance
D) It limits the current flow to a fixed value
Answer: A
16.
For a diode with a 0.7 V forward voltage drop, how much current flows if the
applied forward voltage is 0.9 V?
A) Zero current
B) Small current
C) Large current
D) Infinite current
Answer: C
17.
In a diode, the depletion region is:
A) Free of charge carriers
B) Full of electrons
C) Full of holes
D) Full of ions
Answer: A
18.
A diode has a forward current of 20 mA and a reverse saturation current of 10⁻¹⁴ A.
What is the voltage across the diode when it is forward biased at 0.7 V?
A) 0.7 V
B) 1.0 V
C) 1.2 V
D) 1.5 V
Answer: A
19.
What is the primary purpose of a Zener diode in a circuit?
A) Rectification
B) Voltage regulation
C) Signal amplification
D) Current limiting
Answer: B
20.
If the reverse voltage across a diode exceeds the Zener breakdown voltage, the
diode:
A) Acts as a regular diode
B) Becomes an open circuit
C) Allows current to flow in reverse
D) Stops conducting completely
Answer: C
21.
A diode with a 1N4007 part number is:
A) A Zener diode
B) A Schottky diode
C) A standard rectifier diode
D) A Light Emitting Diode
Answer: C
22.
For a diode in a forward-biased condition, what happens when the temperature
increases?
A) The forward voltage increases
B) The forward voltage decreases
C) The current remains the same
D) The diode becomes reverse biased
Answer: B
23.
What is the typical reverse saturation current for a silicon diode at room
temperature (300 K)?
A) 10⁻³ A
B) 10⁻¹⁴ A
C) 10⁻⁶ A
D) 10⁻⁹ A
Answer: B
24.
In a P-N junction diode, the barrier potential:
A) Is formed when the P-type and N-type materials are brought together
B) Increases when the diode is reverse biased
C) Decreases when the diode is forward biased
D) All of the above
Answer: D
25.
In a diode's forward bias condition, if the current increases significantly with only a
small increase in voltage, what characteristic is being demonstrated?
A) Diode resistance
B) Diode capacitance
C) Diode threshold voltage
D) Diode exponential current-voltage relationship
Answer: D
26.
What is the peak inverse voltage (PIV) for a diode if the maximum reverse current
is 1 mA, and the diode's resistance in reverse bias is 5000 Ω?
A) 5 V
B) 50 V
C) 500 V
D) 5000 V
Answer: B
27.
What will be the voltage across a diode if it is reverse biased and the reverse
saturation current is 10⁻¹⁴ A, while the applied reverse voltage is 20 V?
A) 20 V
B) 0.7 V
C) 0.02 V
D) 0 V
Answer: A
28.
A silicon diode has a reverse saturation current of 10⁻¹² A at 300 K. If the diode is
reverse biased at 0.7 V, what is the reverse current?
A) 10⁻¹² A
B) 10⁻⁹ A
C) 10⁻⁶ A
D) 10⁻³ A
Answer: B
29.
What happens when the forward voltage of a diode exceeds its threshold voltage?
A) The diode stops conducting
B) The current increases rapidly
C) The current decreases
D) The diode becomes reverse biased
Answer: B
30.
If the reverse voltage across a diode exceeds its Zener breakdown voltage, what
occurs?
A) The diode conducts heavily in reverse
B) The diode becomes forward biased
C) The diode breaks down and conducts reverse current
D) The diode does not conduct
Answer: C
31.
A diode has a forward voltage drop of 0.7 V and a resistance of 10 Ω. What current
flows through the diode when a 10 V forward bias is applied?
A) 1 A
B) 0.93 A
C) 1.07 A
D) 2 A
Answer: B
32.
The Zener diode is most commonly used in:
A) Amplifiers
B) Voltage regulators
C) Rectifiers
D) Signal modulators
Answer: B
33.
A diode in a circuit has a 1 V forward bias. The current through the diode is 5 mA.
What is the power dissipation in the diode?
A) 0.5 mW
B) 5 mW
C) 10 mW
D) 1 W
Answer: B
34.
The energy band gap for a silicon semiconductor is approximately:
A) 0.2 eV
B) 1.1 eV
C) 2.0 eV
D) 1.5 eV
Answer: B
35.
In an ideal diode, the reverse current is:
A) Zero
B) Infinite
C) Small but constant
D) Large
Answer: A
36.
In a Schottky diode, the metal-semiconductor junction:
A) Acts as a rectifier
B) Exhibits lower forward voltage
C) Exhibits higher forward voltage
D) Is not capable of rectification
Answer: B
37.
A silicon diode has a forward voltage of 0.7 V and a reverse current of 10⁻¹⁴ A.
What is the total current if the diode is forward biased at 0.8 V?
A) 10⁻¹⁴ A
B) 1 A
C) 10⁻¹⁰ A
D) 10⁻⁶ A
Answer: C
38.
What is the typical value of the reverse breakdown voltage for a Zener diode used
in voltage regulation?
A) 0.7 V
B) 5.1 V
C) 12 V
D) 30 V
Answer: B
39.
If a diode has a reverse current of 10 µA and a forward voltage of 0.7 V, what is the
current flowing when the forward voltage is increased to 1.2 V?
A) 100 µA
B) 1 mA
C) 10 mA
D) 100 mA
Answer: A
40.
If a diode is connected to a 9 V battery with a 470 Ω resistor, what is the current
through the diode if the forward voltage drop across the diode is 0.7 V?
A) 18.5 mA
B) 17 mA
C) 16 mA
D) 20 mA
Answer: A
41.
What does the current-voltage characteristic curve of a diode look like in the
reverse bias region?
A) It shows a straight line
B) It shows exponential growth
C) It remains flat until breakdown voltage
D) It is discontinuous
Answer: C
42.
Which type of diode is commonly used for switching applications due to its high
speed and low forward voltage drop?
A) Schottky diode
B) Zener diode
C) Light Emitting Diode (LED)
D) Tunnel diode
Answer: A
43.
What is the maximum current a diode can safely handle before permanent damage
occurs?
A) Reverse breakdown current
B) Forward current rating
C) Thermal runaway current
D) Rated peak reverse voltage
Answer: B
44.
A P-N junction in a diode is reverse biased. What occurs in the depletion region?
A) No current flows
B) It becomes narrow with an increase in voltage
C) It becomes wide with an increase in voltage
D) It shrinks to zero
Answer: C
45.
What is the forward voltage drop typically associated with a silicon diode?
A) 0.1 V
B) 0.3 V
C) 0.7 V
D) 1.1 V
Answer: C
46.
In an ideal diode, which of the following is true?
A) The diode has zero resistance in forward bias and infinite resistance in
reverse bias
B) The diode behaves as a short circuit in reverse bias
C) The diode has resistance in both bias directions
D) The diode is a conductor in both directions
Answer: A
47.
Which of the following best describes the behavior of a Zener diode in reverse bias
when the voltage exceeds the Zener breakdown voltage?
A) It allows no current to flow
B) It conducts in reverse with a constant voltage drop
C) It stops conducting
D) It behaves like a regular diode
Answer: B
48.
In a diode, the rate at which current increases with respect to the applied forward
voltage is highest when:
A) The voltage is just above the threshold voltage
B) The voltage is very high
C) The voltage is at zero
D) The diode is reverse biased
Answer: A
49.
Which material is commonly used for the construction of diodes?
A) Copper
B) Silicon
C) Gallium
D) Platinum
Answer: B
50.
The reverse saturation current in a diode:
A) Is independent of temperature
B) Increases with increasing temperature
C) Decreases with increasing temperature
D) Does not change with reverse voltage
Answer: B
