Drift current in a semiconductor is caused by the movement of charge carriers (electrons and holes) under the influence of an external electric field. This results in the flow of current in the direction of the electric field.
What is the cause of diffusion current in a semiconductor?
A Electric field
B Temperature gradient
C Carrier concentration gradient
D Magnetic field
Diffusion current is caused by the movement of charge carriers from regions of high concentration to regions of low concentration. This occurs when there is a gradient in the carrier concentration within the semiconductor material.
What is the primary function of a diode?
A Signal modulation
B Current rectification
C Light emission
D Current amplification
The primary function of a diode is to allow current to flow in one direction only, thus rectifying alternating current (AC) into direct current (DC). It is widely used in power supplies and signal processing.
What is the depletion region in a p-n junction?
A Area with high resistance
B Area with high conductivity
C Area with excess charge carriers
D Area with no charge carriers
The depletion region is formed at the p-n junction where electrons and holes recombine, leaving behind immobile ionized atoms. This region acts as a barrier preventing current flow under reverse bias conditions.
What does the Hall effect measure?
A Magnetic field
B Voltage
C Carrier concentration
D Current
The Hall effect measures the transverse voltage generated when a magnetic field is applied perpendicular to the flow of current in a conductor or semiconductor. This voltage is proportional to the magnetic field strength.
In a diode, what happens when the junction is forward biased?
A Current is blocked
B Depletion region shrinks
C Depletion region expands
D Current flows freely
When a diode is forward biased, the p-type side is connected to the positive terminal, and the n-type side to the negative terminal. This reduces the width of the depletion region, allowing current to flow through the diode.
What is the primary purpose of doping in semiconductors?
A Increase conductivity
B Control carrier mobility
C Decrease conductivity
D Increase resistance
Doping introduces impurities into the semiconductor to increase its conductivity. By adding donor or acceptor impurities, the number of charge carriers (electrons or holes) is increased, thus enhancing electrical conduction.
What is the role of the base in a Bipolar Junction Transistor (BJT)?
A Emit charge carriers
B Collect charge carriers
C Amplify signal
D Control current flow
In a BJT, the base controls the flow of current between the collector and emitter. A small current at the base controls a much larger current, enabling the transistor to function as an amplifier.
What does the band gap of a semiconductor determine?
A Current flow
B Resistance
C Conductivity
D Carrier mobility
The band gap of a semiconductor determines its conductivity. A smaller band gap allows electrons to more easily move from the valence band to the conduction band, increasing conductivity. A larger band gap reduces conductivity.
What is the primary function of a Field-Effect Transistor (FET)?
A Switching
B Current amplification
C Voltage regulation
D Signal modulation
A Field-Effect Transistor (FET) operates primarily as a switch. It controls current flow between the source and drain based on the voltage applied to the gate, which modulates the conductivity of the channel.
How is carrier concentration affected by increasing temperature in semiconductors?
A Remains constant
B Decreases
C Increases
D Becomes zero
As temperature increases, more electrons gain enough thermal energy to jump from the valence band to the conduction band. This increases the number of free charge carriers, thus increasing the carrier concentration and conductivity.
What is the primary characteristic of a Schottky diode?
A High forward voltage drop
B Low reverse current
C High forward voltage drop
D Low forward voltage drop
A Schottky diode has a lower forward voltage drop compared to regular diodes, making it ideal for high-speed switching applications. This characteristic results in faster response times and higher efficiency in circuits.
What happens in a semiconductor when it is exposed to light?
A Temperature decreases
B Resistance decreases
C Carrier concentration increases
D Band gap increases
When a semiconductor is exposed to light, photons can excite electrons from the valence band to the conduction band, creating electron-hole pairs. This increases the carrier concentration and enhances the material’s conductivity.
What is the primary advantage of using a Zener diode in voltage regulation?
A High current flow
B Constant voltage output
C High efficiency
D High voltage tolerance
The Zener diode is widely used in voltage regulation due to its ability to maintain a constant output voltage when reverse biased above a specific threshold. It is commonly used to regulate voltage in power supplies.
What is the primary characteristic of intrinsic semiconductors?
A No impurities
B Doped with impurities
C High conductivity
D High resistance
Intrinsic semiconductors are pure materials with no impurities or doping. The conductivity of intrinsic semiconductors depends solely on the temperature, as thermal energy excites electrons from the valence band to the conduction band.