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Basic Electronics MCQs 

1. The basic unit of electric charge is:

(A) Electron


(B) Coulomb


(C) Proton


(D) Neutron



2. The charge on one electron is approximately:

(A) 1.6 × 10⁻¹⁹ C


(B) 3.2 × 10⁻¹⁹ C


(C) 1.6 × 10⁻⁸ C


(D) 3.2 × 10⁻¹⁸ C



3. The material having least resistance is:

(A) Silver


(B) Copper


(C) Aluminum


(D) Iron



4. The device which converts AC into DC is called:

(A) Oscillator


(B) Amplifier


(C) Rectifier


(D) Filter



5. In a semiconductor, the charge carriers are:

(A) Electrons and holes


(B) Only electrons


(C) Only holes


(D) Ions



6. The most commonly used semiconductor material is:

(A) Silicon


(B) Copper


(C) Iron


(D) Silver



7. A diode conducts current in:

(A) No direction


(B) Reverse bias


(C) Both directions


(D) Forward bias



8. The reverse breakdown in a diode occurs due to:

(A) High reverse voltage


(B) High forward current


(C) Temperature drop


(D) Low bias



9. The unit of resistance is:

(A) Ohm


(B) Watt


(C) Volt


(D) Ampere



10. The unit of capacitance is:

(A) Coulomb


(B) Henry


(C) Farad


(D) Ohm



11. The function of a capacitor in an electronic circuit is to:

(A) Store electric charge


(B) Convert energy


(C) Regulate voltage


(D) Amplify signal



12. The color code of a 1 kΩ resistor (±5%) is:

(A) Brown, Black, Orange, Silver


(B) Brown, Black, Red, Gold


(C) Red, Black, Brown, Gold


(D) Yellow, Violet, Red, Gold



13. The transistor is used mainly for:

(A) Induction


(B) Storage


(C) Rectification


(D) Amplification and switching



14. The transistor has how many terminals?

(A) Three


(B) Two


(C) Four


(D) One



15. In a PNP transistor, the majority carriers are:

(A) Holes


(B) Electrons


(C) Both


(D) None



16. The base of a transistor is:

(A) Thick and lightly doped


(B) Thick and heavily doped


(C) Thin and heavily doped


(D) Thin and lightly doped



17. The device which converts DC into AC is called:

(A) Inverter


(B) Rectifier


(C) Filter


(D) Transformer



18. The output of a full-wave rectifier is:

(A) Pure DC


(B) Pulsating DC


(C) AC


(D) Constant voltage



19. A zener diode is used for:

(A) Voltage regulation


(B) Amplification


(C) Switching


(D) Rectification



20. The transistor works in which region as an amplifier?

(A) Breakdown region


(B) Cut-off region


(C) Saturation region


(D) Active region



21. The input impedance of a common-base transistor is:

(A) Low


(B) High


(C) Very high


(D) Medium



22. The output of a NOT gate is:

(A) The inverse of input


(B) Same as input


(C) Double the input


(D) Zero



23. The binary number 1010 equals to decimal:

(A) 8


(B) 12


(C) 10


(D) 14



24. The logic gate which gives output 1 when all inputs are 1 is:

(A) AND gate


(B) OR gate


(C) NAND gate


(D) NOR gate



25. The Boolean expression for an OR gate is:

(A) A + B


(B) A.B


(C) A ⊕ B


(D) A’ + B



26. The most common logic family used today is:

(A) TTL


(B) CMOS


(C) ECL


(D) RTL



27. The term LED stands for:

(A) Light Electric Device


(B) Light Energy Device


(C) Laser Energy Diode


(D) Light Emitting Diode



28. A photodiode works on the principle of:

(A) Light incident changes current


(B) Temperature change


(C) Voltage drop


(D) Sound energy



29. The input to an operational amplifier is:

(A) Constant


(B) Single-ended


(C) Differential


(D) None



30. The gain of an ideal op-amp is:

(A) One


(B) Zero


(C) Infinite


(D) Very low



31. The frequency of DC signal is:

(A) Zero


(B) 50 Hz


(C) 100 Hz


(D) Infinite



32. The function of a filter circuit is to:

(A) Amplify signal


(B) Remove ripples from rectified output


(C) Convert AC to DC


(D) Produce oscillation



33. The device used to generate a repetitive waveform is:

(A) Oscillator


(B) Amplifier


(C) Rectifier


(D) Transformer



34. The component which stores energy in a magnetic field is:

(A) Inductor


(B) Capacitor


(C) Resistor


(D) Transformer



35. The transformer operates on the principle of:

(A) Photoconductivity


(B) Electrolysis


(C) Heating effect


(D) Electromagnetic induction



36. The turn ratio of a step-up transformer is:

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Np’)” /> (B) Ns < Np


Np’)” /> (C) Ns = Np


Np’)” /> (D) Ns = 0



37. The transistor which conducts more current for a small base current is said to have:

(A) High β (beta)


(B) Low β


(C) Constant β


(D) Zero β



38. In an NPN transistor, current flows from:

(A) Base to collector


(B) Emitter to collector


(C) Collector to emitter


(D) Collector to base



39. The main function of a voltage divider bias circuit is to:

(A) Stabilize transistor operation


(B) Increase current


(C) Reduce voltage


(D) Improve gain



40. The device used for measuring current is:

(A) Voltmeter


(B) Ammeter


(C) Ohmmeter


(D) Wattmeter



41. The device used to measure voltage is:

(A) Voltmeter


(B) Ammeter


(C) Wattmeter


(D) Galvanometer



42. The SI unit of power is:

(A) Watt


(B) Volt


(C) Ampere


(D) Joule



43. The transistor works as a switch in which regions?

(A) Breakdown


(B) Active


(C) Cut-off and saturation


(D) Linear



44. The avalanche breakdown occurs in:

(A) Zener diode


(B) LED


(C) Rectifier diode


(D) Transistor



45. The N-type semiconductor is obtained by adding:

(A) Pentavalent impurity


(B) Trivalent impurity


(C) Neutral atom


(D) Magnetic material



46. The P-type semiconductor has:

(A) No holes


(B) Equal electrons and holes


(C) More electrons


(D) More holes than electrons



47. The junction of P-type and N-type semiconductor forms a:

(A) PN junction


(B) Transistor


(C) Resistor


(D) Capacitor



48. The frequency range of audio signals is:

(A) 0 to 10 Hz


(B) 20 Hz to 20 kHz


(C) 100 kHz to 1 MHz


(D) Above 1 MHz



49. The component used for tuning in radios is:

(A) Variable capacitor


(B) Fixed resistor


(C) Inductor


(D) Diode



50. The transistor amplifier output is taken from:

(A) Collector


(B) Base


(C) Emitter


(D) Junction



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