Semiconductors, Diodes, Transistors and Logic

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Semiconductors, Diodes, Transistors and Logic Gates

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Semiconductors, Diodes, Transistors and Logic Gates

20:00

#Question 1 of 20Score: +1.0 / -0.25

Which of the following is a semiconductor?

semiconductor — Answer Key & Explanations (20 Questions)

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Attempt the quiz above first, then review every question with its correct answer and a short explanation below.

Q1.Which of the following is a semiconductor?
- A.copper
- B.rubber
- C.aluminium
- D.silicon✓ Correct Answer
Explanation: Silicon and germanium are the common semiconductors.
Q2.The conductivity of a semiconductor generally:
- A.decreases with a rise in temperature
- B.increases with a rise in temperature✓ Correct Answer
- C.stays constant
- D.becomes zero
Explanation: More charge carriers are freed at higher temperature.
Q3.Adding a small amount of impurity to a pure semiconductor is called:
- A.annealing
- B.galvanising
- C.rectification
- D.doping✓ Correct Answer
Explanation: Doping increases conductivity.
Q4.A p-n junction diode allows current to flow:
- A.equally in both directions
- B.in neither direction
- C.mainly in one direction✓ Correct Answer
- D.only when cold
Explanation: It conducts in forward bias and blocks in reverse bias.
Q5.A transistor has how many terminals?
- A.two
- B.three✓ Correct Answer
- C.four
- D.five
Explanation: They are the emitter, base and collector.
Q6.A solar cell converts:
- A.electrical energy into light
- B.heat into sound
- C.sound into electricity
- D.light energy into electrical energy✓ Correct Answer
Explanation: It works on the photovoltaic effect.
Q7.An n-type semiconductor is made by doping silicon with:
- A.a trivalent impurity such as boron
- B.a noble gas
- C.a halogen only
- D.a pentavalent impurity such as phosphorus✓ Correct Answer
Explanation: The extra electron becomes a free charge carrier.
Q8.A p-type semiconductor is made by doping silicon with:
- A.a pentavalent impurity such as phosphorus
- B.a noble gas
- C.a trivalent impurity such as boron✓ Correct Answer
- D.carbon only
Explanation: It creates holes in the lattice.
Q9.The majority charge carriers in an n-type semiconductor are:
- A.holes
- B.electrons✓ Correct Answer
- C.protons
- D.neutrons
Explanation: In n-type material electrons are the majority carriers, so the donor impurity supplies free charge.
Q10.The majority charge carriers in a p-type semiconductor are:
- A.electrons
- B.neutrons
- C.protons
- D.holes✓ Correct Answer
Explanation: A hole is the absence of an electron that acts as a positive carrier.
Q11.A diode is used as a rectifier to convert:
- A.alternating current into direct current✓ Correct Answer
- B.direct current into alternating current
- C.voltage into resistance
- D.heat into current
Explanation: It passes only half of each AC cycle in half-wave rectification.
Q12.An LED emits light when it is:
- A.forward biased✓ Correct Answer
- B.reverse biased
- C.heated strongly
- D.kept in the dark only
Explanation: Electrons and holes recombine and release energy as photons.
Q13.A transistor can function as:
- A.a battery only
- B.an amplifier and a switch✓ Correct Answer
- C.a resistor only
- D.a transformer
Explanation: It is the building block of electronics.
Q14.Which logic gate gives a high output only when both inputs are high?
- A.OR gate
- B.NOT gate
- C.AND gate✓ Correct Answer
- D.XOR gate
Explanation: Output = A · B.
Q15.The first integrated circuit was demonstrated in 1958 by:
- A.Jack Kilby✓ Correct Answer
- B.Alexander Graham Bell
- C.Thomas Edison
- D.Guglielmo Marconi
Explanation: Kilby worked at Texas Instruments.
Q16.In a p-n junction, the region near the junction lacking free carriers is called the:
- A.conduction band
- B.depletion region✓ Correct Answer
- C.base region
- D.emitter region
Explanation: It acts as a barrier to current flow in reverse bias.
Q17.The energy band gap of silicon is about:
- A.0.01 eV
- B.11 eV
- C.1.1 eV✓ Correct Answer
- D.100 eV
Explanation: Insulators have much larger gaps and conductors none.
Q18.Which pair of gates are called universal gates?
- A.NAND and NOR✓ Correct Answer
- B.AND and OR
- C.NOT and XOR
- D.AND and NOT
Explanation: Any logic circuit can be built from either alone.
Q19.The transistor was invented in:
- A.1927
- B.1967
- C.1947✓ Correct Answer
- D.1887
Explanation: It was developed at Bell Laboratories by Bardeen, Brattain and Shockley.
Q20.In a pure (intrinsic) semiconductor, the number of electrons is:
- A.equal to the number of holes✓ Correct Answer
- B.much greater than holes
- C.zero
- D.much smaller than holes
Explanation: Each freed electron leaves a hole behind.

Which of the following is a semiconductor?

semiconductor — Answer Key & Explanations (20 Questions)

Show

Attempt the quiz above first, then review every question with its correct answer and a short explanation below.

Q1.Which of the following is a semiconductor?
- A.copper
- B.rubber
- C.aluminium
- D.silicon✓ Correct Answer
Explanation: Silicon and germanium are the common semiconductors.
Q2.The conductivity of a semiconductor generally:
- A.decreases with a rise in temperature
- B.increases with a rise in temperature✓ Correct Answer
- C.stays constant
- D.becomes zero
Explanation: More charge carriers are freed at higher temperature.
Q3.Adding a small amount of impurity to a pure semiconductor is called:
- A.annealing
- B.galvanising
- C.rectification
- D.doping✓ Correct Answer
Explanation: Doping increases conductivity.
Q4.A p-n junction diode allows current to flow:
- A.equally in both directions
- B.in neither direction
- C.mainly in one direction✓ Correct Answer
- D.only when cold
Explanation: It conducts in forward bias and blocks in reverse bias.
Q5.A transistor has how many terminals?
- A.two
- B.three✓ Correct Answer
- C.four
- D.five
Explanation: They are the emitter, base and collector.
Q6.A solar cell converts:
- A.electrical energy into light
- B.heat into sound
- C.sound into electricity
- D.light energy into electrical energy✓ Correct Answer
Explanation: It works on the photovoltaic effect.
Q7.An n-type semiconductor is made by doping silicon with:
- A.a trivalent impurity such as boron
- B.a noble gas
- C.a halogen only
- D.a pentavalent impurity such as phosphorus✓ Correct Answer
Explanation: The extra electron becomes a free charge carrier.
Q8.A p-type semiconductor is made by doping silicon with:
- A.a pentavalent impurity such as phosphorus
- B.a noble gas
- C.a trivalent impurity such as boron✓ Correct Answer
- D.carbon only
Explanation: It creates holes in the lattice.
Q9.The majority charge carriers in an n-type semiconductor are:
- A.holes
- B.electrons✓ Correct Answer
- C.protons
- D.neutrons
Explanation: In n-type material electrons are the majority carriers, so the donor impurity supplies free charge.
Q10.The majority charge carriers in a p-type semiconductor are:
- A.electrons
- B.neutrons
- C.protons
- D.holes✓ Correct Answer
Explanation: A hole is the absence of an electron that acts as a positive carrier.
Q11.A diode is used as a rectifier to convert:
- A.alternating current into direct current✓ Correct Answer
- B.direct current into alternating current
- C.voltage into resistance
- D.heat into current
Explanation: It passes only half of each AC cycle in half-wave rectification.
Q12.An LED emits light when it is:
- A.forward biased✓ Correct Answer
- B.reverse biased
- C.heated strongly
- D.kept in the dark only
Explanation: Electrons and holes recombine and release energy as photons.
Q13.A transistor can function as:
- A.a battery only
- B.an amplifier and a switch✓ Correct Answer
- C.a resistor only
- D.a transformer
Explanation: It is the building block of electronics.
Q14.Which logic gate gives a high output only when both inputs are high?
- A.OR gate
- B.NOT gate
- C.AND gate✓ Correct Answer
- D.XOR gate
Explanation: Output = A · B.
Q15.The first integrated circuit was demonstrated in 1958 by:
- A.Jack Kilby✓ Correct Answer
- B.Alexander Graham Bell
- C.Thomas Edison
- D.Guglielmo Marconi
Explanation: Kilby worked at Texas Instruments.
Q16.In a p-n junction, the region near the junction lacking free carriers is called the:
- A.conduction band
- B.depletion region✓ Correct Answer
- C.base region
- D.emitter region
Explanation: It acts as a barrier to current flow in reverse bias.
Q17.The energy band gap of silicon is about:
- A.0.01 eV
- B.11 eV
- C.1.1 eV✓ Correct Answer
- D.100 eV
Explanation: Insulators have much larger gaps and conductors none.
Q18.Which pair of gates are called universal gates?
- A.NAND and NOR✓ Correct Answer
- B.AND and OR
- C.NOT and XOR
- D.AND and NOT
Explanation: Any logic circuit can be built from either alone.
Q19.The transistor was invented in:
- A.1927
- B.1967
- C.1947✓ Correct Answer
- D.1887
Explanation: It was developed at Bell Laboratories by Bardeen, Brattain and Shockley.
Q20.In a pure (intrinsic) semiconductor, the number of electrons is:
- A.equal to the number of holes✓ Correct Answer
- B.much greater than holes
- C.zero
- D.much smaller than holes
Explanation: Each freed electron leaves a hole behind.

Which of the following is a semiconductor?

semiconductor — Answer Key & Explanations (20 Questions)

Related General Physics topics

Which of the following is a semiconductor?

semiconductor — Answer Key & Explanations (20 Questions)

Related General Physics topics