A transistor is primarily used for amplifying electrical signals. By controlling a small input signal at the base, it allows a larger output current to flow from the collector to the emitter, thus amplifying the signal.
What is the effect of applying a reverse bias to a diode?
A It decreases resistance
B It allows current
C It blocks current
D It amplifies signal
When a diode is reverse biased, the p-type is connected to the negative terminal, and the n-type is connected to the positive terminal. This increases the depletion region, effectively preventing the flow of current under normal conditions.
In which region of a BJT does the transistor operate as an amplifier?
A Cutoff
B Saturation
C Active
D Breakdown
The active region of a Bipolar Junction Transistor (BJT) is where it functions as an amplifier. In this region, the base current controls the larger current flowing between the collector and emitter, allowing signal amplification.
What type of material is used for doping semiconductors?
A Phosphorus
B Aluminum
C Gallium
D Copper
Phosphorus is commonly used to dope n-type semiconductors. It has five valence electrons, which provide extra electrons that serve as free charge carriers, increasing the conductivity of the semiconductor material.
What is the role of the gate terminal in a MOSFET?
A Amplify signal
B Emit charge carriers
C Control current
D Collect charge carriers
The gate of a MOSFET controls the flow of current between the source and drain terminals. By applying a voltage to the gate, the conductivity between the source and drain can be modulated, enabling switching and amplification.
What is the characteristic of an intrinsic semiconductor?
A High conductivity
B Low resistance
C Equal number of electrons and holes
D High voltage tolerance
In an intrinsic semiconductor, the number of electrons in the conduction band is equal to the number of holes in the valence band. It behaves as a pure semiconductor without any intentional doping.
What is the most common application of a diode?
A Voltage modulation
B Current rectification
C Signal amplification
D Light detection
The most common application of a diode is rectification, which is converting AC (alternating current) to DC (direct current). This is done by allowing current to flow in only one direction, thus “rectifying” the input signal.
Which of the following describes the behavior of majority carriers in a p-type semiconductor?
A Holes
B Protons
C Electrons
D Neutrons
In a p-type semiconductor, holes are the majority carriers. These holes represent the absence of electrons in the valence band, and they carry a positive charge as they move through the semiconductor material.
What is the effect of temperature on the conductivity of a semiconductor?
A Remains constant
B Decreases
C Increases
D Becomes zero
As the temperature of a semiconductor increases, more electrons acquire enough energy to move from the valence band to the conduction band. This increases the number of charge carriers, thereby enhancing conductivity.
Which material has a larger energy band gap than silicon?
A Germanium
B Aluminum
C Germanium
D Gallium Arsenide
Gallium Arsenide (GaAs) has a larger band gap than silicon, making it more suitable for high-speed and high-frequency applications, such as microwave and optical devices, compared to silicon-based devices.
What defines the cutoff frequency of a transistor?
A Minimum operating voltage
B Frequency where gain is unity
C Frequency where gain is reduced to half
D Maximum signal strength
The cutoff frequency of a transistor is defined as the frequency at which the gain of the transistor falls to unity (1). It marks the transition between the active region and the high-frequency performance limit of the transistor.
What happens when a semiconductor is heavily doped?
A Reduced electron mobility
B Decreased conductivity
C Increased conductivity
D Increased resistivity
Heavily doping a semiconductor adds more charge carriers (either electrons or holes), which increases the material’s electrical conductivity. This is crucial for making highly conductive materials for electronic devices.
What is the role of a photodiode in a circuit?
A Convert light to current
B Store energy
C Regulate voltage
D Amplify signal
A photodiode is used to convert light energy into electrical current through the photovoltaic effect. When light strikes the photodiode, it generates a photocurrent that is used in applications like light sensors and optical communication.
What is the primary function of a BJT’s emitter?
A Control current
B Amplify signal
C Collect charge carriers
D Emit charge carriers
The emitter of a Bipolar Junction Transistor (BJT) emits charge carriers (either electrons or holes) into the base. These carriers are then controlled by the base to allow current to flow between the collector and emitter, enabling amplification.
What is the primary application of CMOS technology?
A Analog circuits
B Signal modulation
C Digital circuits
D High-frequency applications
CMOS (Complementary Metal-Oxide-Semiconductor) technology is primarily used in digital circuits. It is highly efficient, using low power consumption in logic gates, microprocessors, and memory devices, which are the backbone of modern electronics.