What is the primary function of a bipolar junction transistor (BJT)?
A Signal amplification
B Voltage regulation
C Light detection
D Signal modulation
A BJT is primarily used for signal amplification. It uses a small input current at the base to control a larger current between the collector and emitter, amplifying weak signals for various applications in electronics.
What is the key characteristic of a P-channel MOSFET?
A Requires negative gate voltage
B Requires positive gate voltage
C Current flows from drain to source
D Current flows from source to drain
In a P-channel MOSFET, current flows from the drain to the source when a negative voltage is applied to the gate. This makes it a key component in digital logic and power switching applications.
Which of the following defines a photodiode’s primary function?
A Control voltage
B Convert light into current
C Amplify current
D Store energy
A photodiode is designed to convert light into an electrical current through the photovoltaic effect. It is widely used in light sensors, cameras, and optical communication systems.
What is the effect of increasing the temperature on the current in a semiconductor?
A Current decreases
B Current stays constant
C Current becomes zero
D Current increases
As the temperature increases, more electrons gain enough energy to jump from the valence band to the conduction band, which increases the carrier concentration, and consequently, the current in a semiconductor.
Which region of a transistor is responsible for controlling current flow?
A Collector
B Base
C Emitter
D Drain
In a Bipolar Junction Transistor (BJT), the base controls the flow of current between the collector and emitter. A small base current regulates the larger current, allowing the transistor to act as an amplifier or switch.
What does the cutoff region of a BJT refer to?
A Transistor is off
B Transistor is saturated
C Transistor is amplifying
D Transistor is in reverse bias
In the cutoff region, the transistor behaves like an open switch. The base-emitter junction is not forward biased, meaning no current flows from the collector to the emitter, and the transistor is essentially “off.”
What defines the operating region of a Field-Effect Transistor (FET)?
A Output current
B Source voltage
C Gate voltage
D Input voltage
The operating region of a FET is determined by the voltage applied to the gate terminal. This voltage controls the flow of current between the source and drain, allowing the transistor to act as a switch or amplifier.
Which of the following is the primary role of a phototransistor?
A Voltage regulation
B Signal amplification
C Current rectification
D Light detection
A phototransistor is designed to detect light and convert it into an electrical signal. It works similarly to a regular transistor but is sensitive to light and used in applications like optical sensing and communication.
What happens when a semiconductor is exposed to a photon of sufficient energy?
A It excites an electron
B It generates current
C It creates a hole
D It induces resistance
When a photon of sufficient energy strikes a semiconductor, it excites an electron from the valence band to the conduction band, creating an electron-hole pair. This phenomenon is crucial for photodetectors and photovoltaic cells.
What is the primary difference between a P-channel and an N-channel MOSFET?
A Source-drain direction
B Type of current carrier
C Gate voltage polarity
D Current flow speed
In a P-channel MOSFET, holes are the majority carriers, while in an N-channel MOSFET, electrons are the majority carriers. This difference affects their operation and applications in electronic circuits.
What is the forward voltage drop across a silicon diode?
A 1.1V
B 0.3V
C 0.7V
D 0.1V
The typical forward voltage drop across a silicon diode is around 0.7V when it is conducting. This voltage is required to overcome the barrier potential of the p-n junction and allow current to flow.
What is the effect of increasing the carrier concentration in a semiconductor?
A Increases resistance
B Decreases resistance
C No effect on conductivity
D Increases temperature
Increasing the carrier concentration in a semiconductor by doping or changing temperature decreases its resistance. More charge carriers (electrons or holes) are available for conduction, improving the material’s conductivity.
What is the primary function of a BJT’s collector?
A Store charge
B Control voltage
C Collect current
D Emit current
The collector in a Bipolar Junction Transistor (BJT) collects the charge carriers that flow from the emitter through the base. It is responsible for collecting the amplified current that exits the transistor.
What type of current does a photovoltaic cell generate?
A Pulsating current
B High-frequency current
C Direct current (DC)
D Alternating current (AC)
A photovoltaic cell generates direct current (DC) when it converts light energy into electrical energy. The electrons excited by light flow in a single direction, producing a unidirectional current.
What happens when a transistor is in the saturation region?
A It behaves as a switch
B It stops conducting
C It amplifies signals
D It is in cutoff mode
In the saturation region, a transistor behaves like a closed switch. The collector-emitter voltage drops to a minimal level, and the transistor conducts the maximum current, typically used for switching applications.