38 Questions
What type of semiconductor material is needed to make a p-type?
Trivalent
What is the voltage drop across a combination of a silicon diode and a germanium diode connected in series?
The sum of the voltage drops across the two diodes
What is the point of intersection between the characteristic curve of the diode and the resistor's loadline known as?
All of the above
What is the direction of the arrow in the diode symbol?
From p-type of semiconductor to n-type semiconductor material
What happens to the reverse saturation current of a diode with every 10°C rise in the diode temperature?
Doubles
What happens to the forward current of a forward-biased diode when the temperature increases?
Causes forward current to increase
What is the piecewise linear model, equivalent circuit of the diode composed of?
A resistor and a voltage source
What is the DC voltage on the load considering the voltage drop across the Diodes?
15.563V
What is the DC power supplied to the load?
0.2400W
What is the type of semiconductor material obtained by introducing pentavalent impurities into silicon?
N-type
What is the conversion efficiency of this rectifier?
0.7685pu
What is the peak value of the AC current?
0.02400A
What is the RMS value of the current supplied to the circuit?
0.017680A
What is the AC power supplied to the whole circuit?
0.31267A
What determines the energy level of an electron in an atom?
The distance from the electron to the nucleus
Which of the following statements about an electron's energy level is true?
Electrons in the innermost shell have the highest energy level
What is the characteristic of a linear component?
The current is proportional to the applied voltage
Which of the following is an example of a linear component?
Resistor
What is Ohm's law?
A law that states that current is proportional to voltage
What is the relationship between voltage and current in a linear component?
Direct
What is the characteristic of a non-linear component?
The current is non-proportional to the applied voltage
What is the purpose of the scannable sheet in the examination?
To submit the answers to the questions
What components are required to test a diode?
A battery, a small resistor, and the ideal diode
What should the resistances of a diode be in the forward and reverse directions?
Relatively low in the forward direction and relatively high in the reverse direction
What region occurs when the diode is reverse-biased?
Depletion region
What happens to the current and voltage across the diode in the Zener region?
The current can increase a lot and the voltage is almost constant
Under what condition does the diffusion capacitance of a diode occur?
When the diode is large
When does a light-emitting diode emit light?
When the p-n junction is forward-biased
What type of capacitance occurs when the diode is reverse-biased?
Transition capacitance
What are the two most common semiconductor materials?
Silicon and germanium
What has led to the primary purpose of the container being to provide a means for physical handling?
The miniaturization of electronic devices
What type of impurities cause holes to be the majority carriers?
Hexavalent impurities
What is an advantage of the miniaturization of electronic devices?
They are more compact
Which device is roughly equivalent to a diode?
A one-way valve
What is the purpose of a diode test setting on an ohmmeter?
To test the diode in the forward and reverse directions
What is the ideal diode used for in testing?
To simulate an ideal diode characteristic
What happens to the depletion region when a diode is reverse-biased?
It grows
What is a conducting forward-biased diode equivalent to?
A closed switch
Study Notes
COE/EE 152: BASIC ELECTRONICS
Energy Level of Electrons
- Energy level of an electron: Electrons in the outermost shell have the highest energy level.
Linear Component
- Linear component: an increase in current is proportional to the applied voltage as given by Ohm's law.
- Example of a linear component: Resistor.
Semiconductor Material
- Doping material needed to make a p-type semiconductor material: trivalent.
- Doping material needed to make an n-type semiconductor material: pentavalent.
Diodes
- The point of intersection between the characteristic curve of the diode and the resistors loadline: Q-point or point of operation or quiescent point.
- Direction of the arrow in the diode symbol: from p-type of semiconductor to n-type semiconductor material.
- Reverse saturation current of a diode: doubles for every 10°C rise in the diode temperature.
- Effect of increasing temperature on a forward-biased diode: increases forward current.
Diode Testing
- Testing a diode with an ohmmeter: check its resistance in the forward and reverse direction.
- Resistances of a diode: relatively low in the forward direction and relatively high in the reverse direction.
Zener Region
- Current in the Zener region: can increase a lot.
- Voltage across the diode in the Zener region: is almost constant.
Light-Emitting Diodes
- Conditions for light emission in a p-n junction: forward-biased.
Semiconductor Devices
- Advantage of miniaturization: they operate more efficiently.
- Container purpose: provide a means for physical handling.
Capacitance
- Diffusion capacitance: a shunt capacitance effect that occurs when the diode is forward-biased.
- Transition capacitance: a shunt capacitive effect that occurs when the diode is reverse-biased.
Semiconductor Materials
- Two most common semiconductor materials: Silicon and Germanium.
Doping
- Doping: the process of adding impurities to pure semiconductor material.
- Effect of trivalent impurities: cause holes to be the majority carriers.
- Effect of pentavalent impurities: cause electrons to be the majority carriers.
Diode Equivalent
- Device roughly equivalent to a diode: a one-way valve.
Depletion Region
- Depletion region: acts as an insulator and the dielectric value is proportional to barrier potential.
- Effect of reverse bias on the depletion region: it increases.
Forward-Biased Diode
- A conducting forward-biased diode: behaves like a short circuit.
Rectifier Circuits
- DC Voltage on the load: depends on the voltage drop across the diodes.
- DC power supplied to the load: depends on the voltage drop across the diodes and the load resistance.
- Conversion efficiency of a rectifier: depends on the AC voltage, DC voltage, and power supplied.
- Peak value of the AC current: depends on the load resistance and the AC voltage.
- RMS value of the current supplied to the circuit: depends on the load resistance and the AC voltage.
- AC power supplied to the whole circuit: depends on the voltage and current.
Mid-semester exam questions for B.Sc. Engineering 1st year students at Kwame Nkrumah University of Science and Technology, covering basic electronics topics.
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