ET 212 Final Examination Answers – Grantham

Select True / False from the following :

Question 1

The two basic kinds of transistor circuits are amplifying and switching.

True

False

Question 2

The bridge rectifier is similar to a full-wave rectifier because it produces a full-wave output voltage.

True

False

Question 3

A semiconductor is an element with electrical properties between those of a conductor and those of an insulator.

True

False

Question 4

The dc beta is defined as the dc collector current divided by the dc emitter current.

True

False

Question 5

An ideal diode acts like a switch that closes when forward-biased and opens when reverse-biased.

True

False

Question 6

With a half-wave rectifier, the output frequency equals the input frequency.

True

False

Select Correct Answers from the Following

Question 7

A pure semiconductor is also referred to as:

		a clean room device
		intrinsic
		extrinsic
		Transistor

4 points

Question 8

Silicon that has been doped with a trivalent impurity is called a:

		N-type semiconductor
		P-type semiconductor
		P-N junction
		covalent bond

4 points

Question 9

In a silicon atom, what is the distance between the valence band and the conduction band called?

		energy gap
		depletion layer
		P-N junction
		intrinsic

4 points

Question 10

A diode is a nonlinear device because the graph of its current versus voltage is:

		a straight line
		not a straight line
		inversely proportional to the resistance
		exponential

4 points

Question 11

Ideally, a diode acts like a perfect conductor when forward-biased and:

		like a perfect conductor when reverse-biased
		like a perfect semiconductor when reverse-biased
		like a perfect insulator when reverse-biased
		like a perfect diode when reverse-biased

4 points

Question 12

A diode that exhibits high resistance in both directions when measured with an ohmmeter is:

		shorted
		leaky
		open
		a properly operating diode

4 points

Question 13

The knee voltage of a germanium diode is approximately ________.

		0.7 V
		0.3 V
		1.7 V
		1.3 V

4 points

Question 14

Much of the information on a manufacturer’s data sheet is:

		necessary to understand diode circuits
		necessary to troubleshoot diode circuits
		obscure and of use only to circuit designers
		necessary only to electronics technicians

4 points

Question 15

The output frequency of a half-wave rectifier is:

		twice the input frequency
		half the input frequency
		equal to the input frequency
		four times the input frequency

4 points

Question 16

A step-up transformer will produce a secondary voltage that is:

		smaller than the primary
		equal to the primary
		larger than the primary
		rectified.

4 points

Question 17

What is the name of the circuit shown in the Figure 1 below?

Figure 1

		half-wave rectifier
		full-wave rectifier
		bridge rectifier
		voltage doubler

4 points

Question 18

Which region of the transistor is physically the largest?

		collector
		emitter
		base
		beta

4 points

Question 19

Kirchhoff’s current law describes transistor currents as follows:

		emitter current equals the sum of collector and base currents.
		collector current equals the sum of base and emitter currents.
		base current equals the sum of collector and emitter currents.
		emitter current equals collector current minus the base current.

4 points

Question 20

Refer to Figure 2 below, what is the possible problem if VB is equal to 0 V and VC is equal to 15 V?

Figure 2

		transistor is shorted
		RB is open
		VCC is 0 V
		transistor is blown open

4 points

Question 21

Refer to Figure 2, what is the possible problem if VB is equal to 15 V and VC is equal to 15 V?

Figure 2

		transistor is blown open
		VBB is 0 V
		transistor is shorted
		VCC is 0 V

4 points

Question 22

Using the load line shown in Figure 3, what is the transistor’s collector current if biased at the point labelled Q?

Figure 3

		1.5 mA
		3 mA
		4.5 mA
		7 mA

4 points

Question 23

In the circuit shown in the Figure 4 below, calculate the saturation current?

Figure 4

4 points

Question 24

In the Common Collector (CC) circuit of Figure 5 below consider β = 49 and VBE = 0.7 V.

Figure 5

Find the following:

VCE

20 points