Basic Electronics Questions

Basic Introduction Questions

1. What is an ideal voltage  source?

Answer:  Ideal voltage source is defined as the energy source which gives constant voltage across its terminals irrespective of the current drawn through its terminals.

In other words the voltage source (D.C or A.C) will be called ‘ideal’.                        

2. What is an ideal current source?


  • Ideal current source is the source which gives constant current an its terminals irrespective of the voltage appearing across its terminals.
  • Ideal current source is the source which supplies a constant current to a load even if  its impedance varies.

3. What is a practical voltage source?

Answer: A practical voltage source is that which has very low internal resistance(or impedance) as compared to load resistance (or impedance).

4. What is a practical current source?

Answer:  In most applications, ideal source are approximation. The internal resistance Rin of a voltage source, which responsible for a drop in terminal voltage of a source on load is quite small in comparison to the load resistance of a network connected across the voltage source. 

5. The voltage out of an ideal voltage source is

Answer:  Constant

6. The current out of an ideal current source is

Answer:  Constant

7. The path between two points along which an electrical current can be carried is called

Answer:  Circuit

8. The formula for current as per Ohm’s Law is

Answer:  Voltage/resistance

9. The unit of electrical resistance is

Answer: Ohm

10. In a constant voltage DC circuit, when the resistance increases, the current will

Answer: Decrease

Basic Semiconductor Theory Questions

1. Number of valence electrons in a silicon atom are

Answer: 4

2. The most commonly used semiconductor element is

Answer: Silicon

3. Copper is a

Answer: Conductor

4. Number of protons in the nucleus of a silicon atom are

Answer: 14

5. The valence electron of a conductor are also called as

Answer: Free electron

6. An intrinsic semiconductor at room temperature has

Answer: A few electrons and holes

7. At room temperature, an intrinsic semiconductor has some holes in it due to

Answer: Thermal energy

8. The number of holes in an intrinsic semiconductor is

Answer: Equal to number of electrons

9. Holes act as

Answer: Positive Charge

10. To produce P-type semiconductors, you need to add

Answer: Trivalent impurity

11. Electrons are the minority carriers in

Answer:  N-type of semiconductor

12. A p-type semiconductor contains

Answer: Holes and Negative ions

13. How many electrons does pentavalent atoms have?

Answer: 5

14. Negative ions are

Answer: Atoms that lost an electron


Basic Semiconductor Diode Questions

1. Depletion layer is caused by _________

Answer: Doping

2. The reverse current in a diode is usually

Answer: Very small

3. Avalanche in Diode occurs at

Answer: Knee voltage

4. The potential barrier of a silicon diode is

Answer: 0.7 voltage

5. The reverse saturation current in a Silicon Diode is _____ than that of Germanium Diode

Answer: Lower

6. A Diode is a

Answer: Linear device

7. The diode current is large for which condition

Answer: Forward bias.

8. The output voltage signal of a bridge rectifier is

Answer: Full wave rectifier

9. If the maximum DC current rating of diodes in Bridge Rectifier is 1A, what is the maximum DC load current?

Answer: 2A

10. Voltage multipliers produce ?

Answer: High voltage and low current.

11. What is a Clipper?


  •  A wave shaping circuit which controls the shape of output waveform by removing a portion of the applied wave is known as clipping.
  • For a clipping circuit at least one resistance and one diode is required.

12. What is a Clamper?

Answer: A clamping circuit is a device that ‘clamps’ a signal to a different DC level. A clamping circuit must have a diode, a resistance and a capacitor, an independent DC supply is also required to introduce an additional shift.

13. Zener diode can be described as.

Answer: A Device with constant voltage.

14. If the Zener Diode is connected in wrong polarity, the voltage across the load is

Answer: 0.7 Voltage

Basic Transistor Questions


1. Number of PN Junctions in a Transistor

Answer: Two

2. The doping concentration of Base in NPN Transistor is

Answer: Lightly doped

3. The Base – Emitter Diode (Base – Emitter Junction) in an NPN Transistor is

Answer: Forward biased

4. The size comparison between Base, Emitter and Collector is

Answer: Collector > Emitter > Base

5. The Base – Collector Diode (Base Collector Junction) is usually

Answer: Reversed biased

6. The DC Current Gain of a Transistor is

Answer: Ratio of collector current to base current

7. If base current is 100µA and current gain is 100, then collector current is

Answer: 10mA

8. The majority carriers in NPN and PNP Transistors are

Answer: Electrons and Holes

9. A Transistor acts as a

 Answer: Diode and current source

10. The relation between Base Current IB, Emitter Current IE and Collector Current IC is

Answer: IE = IB+ IC

11. The total power dissipated by a transistor is a product of collector current and

Answer: Collector- emitter voltage

12. The input impedance of Common Emitter Configuration is

Answer: Low

13. The output impedance of Common Emitter Configuration is

Answer: High

14. The current gain in Common Base configuration (α) is

Answer: Ratio of collector current to emitter current (IC/IE)

15. Relation between α and ß is

Answer: ß = α / (1 – α)





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