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Let us help each other, fellow ECE reviewees and students. Do not result to such lowly behavior.
As they say, a rising tide floats all boats. Lets mind our manners. Respect, engineers.
Good for testing your knowledge and mastery on different review materials. Question bank inlcudes Malvino

• 1.

### An ideal voltage source has

• A.

Zero internal resistance

• B.

Infinite internal resistance

• C.

• D.

A. Zero internal resistance
Explanation
An ideal voltage source has zero internal resistance because it is able to provide a constant voltage regardless of the load connected to it. This means that the voltage source can deliver the same voltage without any loss or drop in voltage due to internal resistance. Therefore, the ideal voltage source is considered to have zero internal resistance.

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• 2.

### A real voltage source has

• A.

Zero internal resistance

• B.

Infinite internal resistance

• C.

A small internal resistance

• D.

A large internal resistance

C. A small internal resistance
Explanation
A real voltage source typically has a small internal resistance. This means that the voltage source can deliver a relatively large amount of current without a significant drop in voltage. A small internal resistance allows for efficient transfer of electrical energy from the source to the connected load.

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• 3.

### The net charge of a neutral copper atom is

• A.

0

• B.

+1

• C.

- 1

• D.

+4

A. 0
Explanation
A neutral copper atom has an equal number of protons and electrons. Protons have a positive charge, while electrons have a negative charge. Since the number of positive charges is balanced by the number of negative charges, the overall charge of a neutral copper atom is 0.

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• 4.

### At room temperature an intrinsic silicon crystal acts approximately like

• A.

Battery

• B.

Conductor

• C.

Insulator

• D.

Piece of copper wire

C. Insulator
Explanation
At room temperature, an intrinsic silicon crystal acts like an insulator. This is because the electrons in the crystal's valence band are tightly bound to their atoms and do not have enough energy to move freely. Therefore, the crystal does not conduct electricity well. However, when the temperature increases or the crystal is doped with impurities, it can become a conductor.

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• 5.

### What causes the depletion layer?

• A.

Doping

• B.

Recombination

• C.

Barrier Potential

• D.

Ions

B. Recombination
Explanation
Recombination is the process in which an electron from the conduction band recombines with a hole in the valence band, resulting in the release of energy. This recombination process leads to the formation of a depletion layer in a semiconductor. As electrons and holes recombine, they neutralize each other, creating a region with no free charge carriers. This region is known as the depletion layer, which acts as a barrier to the flow of current in a semiconductor device.

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• 6.

### With a half-wave rectified voltage across the load resistor, load current flows for what part of a cycle?

• A.

0 degrees

• B.

90 degrees

• C.

180 degrees

• D.

360 degrees

C. 180 degrees
Explanation
In a half-wave rectified voltage, the load current flows for only half of the cycle. This means that the load current flows for 180 degrees of the cycle. During the positive half-cycle of the input voltage, the diode conducts and allows the current to flow through the load resistor. However, during the negative half-cycle, the diode blocks the current flow, resulting in no current through the load resistor. Therefore, the load current flows for 180 degrees of the cycle.

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• 7.

### The load voltage is approximately constant when a zener diode is

• A.

Forward-biased

• B.

Reverse-biased

• C.

Operating in the breakdown region

• D.

Unbiased

C. Operating in the breakdown region
Explanation
When a zener diode is operating in the breakdown region, it is able to maintain a relatively constant voltage across its terminals regardless of changes in the input voltage. This is because the zener diode is designed to operate in this region and has a specific breakdown voltage. As a result, it can regulate the voltage and keep it stable, making the load voltage approximately constant. In contrast, when the zener diode is forward-biased, reverse-biased, or unbiased, it does not exhibit the same voltage regulation capabilities.

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• 8.

### For typical operation, you need to use reverse bias with a

• A.

Zener diode

• B.

Photodiode

• C.

Varactor

• D.

All of the above

D. All of the above
Explanation
All of the above options require the use of reverse bias for typical operation. A Zener diode is designed to operate in reverse breakdown region, allowing it to regulate voltage. A photodiode also operates in reverse bias to generate a photocurrent when exposed to light. Similarly, a varactor diode is used in reverse bias to vary its capacitance, making it suitable for use in tuning circuits. Therefore, all three options mentioned in the question require reverse bias for their intended operation.

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• 9.

### . If the depletion layer gets wider, the capacitance

• A.

Decreases

• B.

Stays the same

• C.

Increases

• D.

Is variable

A. Decreases
Explanation
When the depletion layer gets wider, it means that the distance between the positive and negative charges in a capacitor increases. This increased distance leads to a decrease in the capacitance of the capacitor. Capacitance is directly proportional to the surface area of the plates and inversely proportional to the distance between them. Therefore, as the depletion layer widens, the capacitance decreases.

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• 10.

### The currents of a pnp transistor are

• A.

Usually smaller than npn currents

• B.

Opposite npn currents

• C.

Usually larger than npn currents

• D.

Negative

B. Opposite npn currents
Explanation
The correct answer is "Opposite npn currents." In a pnp transistor, the direction of current flow is opposite to that of an npn transistor. In an npn transistor, the current flows from the emitter to the base and then to the collector. However, in a pnp transistor, the current flows from the emitter to the base and then to the collector in the opposite direction. Therefore, the currents in a pnp transistor are opposite to the currents in an npn transistor.

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• Current Version
• Jul 17, 2024
Quiz Edited by
ProProfs Editorial Team
• Jun 24, 2011
Quiz Created by
Blogblog1968

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