Physics: Conductors vs. Semiconductors

Questions and Answers

What does a very large change in VCE indicate about IC in the active region?

IC remains constant regardless of VCE.

IC changes significantly with VCE.

Very small changes in IC occur despite large VCE changes. (correct)

IC becomes negative when VCE is increased.

What is the relationship expressed in the output resistance formula Ro?

Ro = ΔVCE / ΔIC │IB is constant. (correct)

Ro = VCE / IC │IB is zero.

Ro = ΔIC / ΔVCE │IB is constant.

Ro = IC / IB │VCE is constant.

In the CC configuration, what is taken between the emitter and collector?

Output voltage (Vout) (correct)

Voltage across VCB

Input current (IB)

Input voltage (Vi)

Which region is characterized by IB being nearly zero?

Cut-off region Signup and view all the answers

What does the output current IE represent in the CC configuration?

Emitter current Signup and view all the answers

What happens to the potential barrier during reverse biasing of a p-n junction?

It increases, preventing charge carrier flow. Signup and view all the answers

When applying reverse bias to a p-n junction, which battery terminal is connected to the p-type material?

Negative terminal Signup and view all the answers

What is the result of establishing an electric field in the same direction as the potential barrier in reverse biasing?

It strengthens the potential barrier. Signup and view all the answers

What type of path is established in the circuit when reverse bias is applied to a p-n junction?

High resistance path Signup and view all the answers

Which statement best describes the flow of current when reverse bias is applied to a p-n junction?

Current is blocked from flowing. Signup and view all the answers

What is the role of a transistor in the scenario described?

It amplifies weak signals. Signup and view all the answers

Which statement accurately describes bias stabilization?

It ensures the operating point remains fixed despite temperature changes. Signup and view all the answers

What causes bias instability in transistors?

Changes in temperature and current gain. Signup and view all the answers

How does temperature affect the base-emitter voltage (VBE) of a transistor?

VBE increases at a rate of 2.4mV/°C. Signup and view all the answers

What is the effect of an increase in reverse saturation current (ICBO) due to rising temperature?

It increases the collector current (IC) and shifts the Q-point. Signup and view all the answers

What is the primary purpose of proper biasing in a transistor circuit?

To ensure the Q-point is at the center of the load line. Signup and view all the answers

What could happen to the Q-point with fluctuations in the current gain (β)?

The Q-point may shift, affecting stability. Signup and view all the answers

What is represented by IC in the equation IC = βIB + (1 + β) ICBO?

The collector current. Signup and view all the answers

What primarily causes current flow in good conductors?

Free electrons Signup and view all the answers

Which of the following statements is true regarding semiconductors?

Electrons and holes move in opposite directions. Signup and view all the answers

What distinguishes an intrinsic semiconductor?

It is extremely pure. Signup and view all the answers

Which of the following is an example of an intrinsic semiconductor?

Silicon Signup and view all the answers

At low temperatures, what happens to the valence electrons in intrinsic semiconductors?

They are tightly bound to the nucleus. Signup and view all the answers

Which of the following charge carriers are present in semiconductors?

Electrons and holes Signup and view all the answers

What is the unit of electric current?

Ampere Signup and view all the answers

What property must an intrinsic semiconductor possess?

Extreme purity Signup and view all the answers

What happens to electrons in a Zener diode during Zener breakdown?

They break their covalent bonds due to a high electric field. Signup and view all the answers

What effect does increasing the reverse voltage have on the electric field in a Zener diode?

It produces a very high intensity electric field. Signup and view all the answers

In a Zener voltage regulator circuit, what does the Zener diode maintain across the load?

The constant voltage VZ. Signup and view all the answers

What is the role of the series resistance Rs in a Zener voltage regulator?

To absorb fluctuations in the current. Signup and view all the answers

What condition must be satisfied for the Zener diode to maintain a constant voltage VZ?

The input voltage must exceed the breakdown voltage VZ. Signup and view all the answers

What characterizes the depletion region in a Zener diode as the reverse voltage increases?

It narrows, causing higher electric field intensity. Signup and view all the answers

What happens during Zener breakdown that allows for a large reverse current to flow?

A high number of electrons break their covalent bonds. Signup and view all the answers

Which component in the Zener voltage regulator circuit is vital for stabilizing voltage during fluctuations?

The Zener diode itself. Signup and view all the answers

Study Notes

Conductors vs. Semiconductors

Conductors (metals) allow current flow solely through free electrons.
In semiconductors, current flow involves both electrons and holes moving in opposite directions.
Electric current is measured in Amperes (A), with charge carriers being electrons and holes.

Types of Semiconductors

Semiconductors are classified into:
- Intrinsic Semiconductors: Extremely pure forms, like Silicon and Germanium, both of which are tetravalent (4 valence electrons).
- Extrinsic Semiconductors: Impurities are added to modify electrical properties.

Characteristics of Intrinsic Semiconductors

At low temperatures, valence electrons are tightly bound, resulting in no free electrons for conduction.

P-N Junction Biasing

Forward Biasing: Current flows easily when the p-type and n-type materials are properly connected.
Reverse Biasing: Elevated potential barrier prevents current flow. The negative terminal of a battery is connected to p-type, and the positive terminal to n-type.

Zener Breakdown

Occurs when reverse voltage creates a high electric field, leading to a large reverse current as electrons break free from their covalent bonds.
The critical relationship: Electric field strength is proportional to reverse voltage over the depletion region.

Zener Voltage Regulator

Connected in reverse bias across a load, stabilizing the output voltage VZ across the load until it drops below the Zener breakdown threshold.
Series resistance (Rs) prevents current fluctuations.

Transistor Output Characteristics

Output characteristics curve illustrates the relationship between collector-emitter voltage (VCE) and collector current (IC) at constant base current (IB).
High output resistance indicated by minimal IC change with large VCE alterations.

CC Configuration

Input connected between the base and collector; output taken between the emitter and collector.
The configuration utilizes input current (IB) and output current (IE).

Current Relations and Amplification

The current amplification factor (γ) indicates how much the input current is amplified.
Transistors amplify weak input signals, producing higher output voltages across load resistance.

Bias Stabilization

Stabilization aims to maintain a fixed operating point, counteracting temperature variations and parameter changes in transistors.
Ensures the Q-point remains stable within the load line.

Causes of Bias Instability

Influenced mainly by:
- Temperature: Increases base-emitter voltage (VBE) by 2.4 mV/°C, impacting base current (IB) and consequently collector current (IC).
- Current Gain (β): Variability among transistors of the same type can result in differences in β, affecting stability and performance.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Explore the differences between conductors and semiconductors in this quiz. Understand the flow of electrons and current in both types of materials. Test your knowledge of electrical properties and applications.