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# Multiple Choice Quiz: Semiconductors

Question 1:

Zener diodes exhibit:

(a) an abrupt reverse breakdown
(c) no breakdown at all

Question 2:

In a semiconductor diode, the depletion region is removed when:

(a) the diode is in its forward conducting state
(b) the diode is in its reverse non-conducting state
(c) there is no potential difference between the anode and cathode

Question 3:

The following data refers to an experiment carried out on a Zener diode:

Reverse voltageReverse current
1 V1 ľA
2 V2 ľA
3 V10 ľA
4 V20 ľA

The Zener voltage will be between:

(a) 1 V and 2 V
(b) 2 V and 3 V
(c) 3 V and 4 V

Question 4:

Which one of the following is TRUE of a two-input OR gate?

(a) a logic 1 output will be produced only when both inputs are at logic 1
(b) a logic 1 output will be produced when only one of the two inputs is at logic 1
(c) a logic 1 output will be produced when one or both of the two inputs is at logic 1

Question 5:

The truth table shown is for a two-input:

(a) NAND gate
(b) NOR gate
(c) Exclusive-OR gate

Question 6:

The forward threshold voltage for a germanium diode is about:

(a) 0.2 V
(b) 0.4 V
(c) 0.6 V

Question 7:

The truth table shown is for a two-input:

(a) NAND gate
(b) NOR gate
(c) Exclusive-OR gate

Question 8:

The typical operating current for a light-emitting diode is approximately:

(a) 1 to 5 mA
(b) 5 to 20 mA
(c) 20 to 500 mA

Question 9:

Which one of the following Boolean expressions is correct for an exclusive-OR gate?

(a) A +
(b) A . B + .
(c) A . + B.

Question 10:

In normal (conducting) operation, the voltage that will appear between the base and emitter of an NPN bipolar junction transistor will be approximately:

(a) 0.15 V
(b) 0.25 V
(c) 0.65 V

Question 11:

The term 'covalent bonding' refers to:

(a) the introduction of an impurity
(b) the sharing of valence electrons
(c) the generation of surplus electrons

Question 12:

When a diode is in its non-conducting state it has:

(a) a very low resistance
(b) a very high resistance
(c) no resistance at all

Question 13:

The zone in a semiconductor diode where no free charge carriers exists is known as the:

(a) anode region
(b) cathode region
(c) depletion region.

Question 14:

It is required to change a logic 0 state into a logic 1 state, and vice versa.

The logic gate required to do this is known as:

(a) a buffer
(b) an inverter
(c) an exclusive-OR gate

Question 15:

The collector current in a bipolar junction transistor is 2 mA when the base current is 0.1 mA. Which one of the following gives the emitter current?

(a) 1.9 mA
(b) 2.1 mA
(c) 20 mA

Question 16:

The Boolean expression for the output of a two-input AND gate is:

(a) A B
(b) A . B
(c) A + B

Question 17:

In an NPN bipolar junction transistor the connections are arranged as follows:

(a) base to P-type, emitter to N-type material, collector to N-type
(b) base to N-type, emitter to N-type material, collector to P-type
(c) base to N-type, emitter to P-type material, collector to N-type

Question 18:

The collector current in a bipolar junction transistor is 2 mA when the base current is 0.1 mA. Which one of the following gives the value of common-emitter current gain?

(a) 1.9
(b) 2.1
(c) 20

Question 19:

The forward threshold voltage for a silicon diode is about:

(a) 0.15 V
(b) 0.25 V
(c) 0.65 V

Question 20:

When a diode is in its conducting state:

(a) current flows from anode to cathode
(b) current flows from cathode to anode
(c) no current flows in the diode

Question 21:

In a metal-cased bipolar transistor, which of the three connections of the transistor are often connected directly to the conducting case?

(a) base
(b) collector
(c) emitter

Question 22:

Which one of the following gives the relationship between the three currents flowing in a bipolar junction transistor?

(a) IE = IB + IC
(b) IB = IE + IC
(c) IC = IB + IE

Question 23:

How many electrons are present in the outer valence shell of a silicon atom?

(a) 1
(b) 2
(c) 4

Question 24:

The three terminals of a bipolar junction transistor are known as:

(a) source, gate, collector
(b) emitter, gate, collector
(c) emitter, base, collector