All Free Electrical Engineering MCQs with Answers

• A. 0 %
• B. 5 %
• C. 10 %
• D. 8%

Explanation: An unregulated supply has a substantial change between no-load and full-load voltage; in standard basic-electronics MCQs, about 10%…

• A. 0%
• B. 5%
• C. 10%
• D. 1%

Explanation: Voltage regulation measures the change in output voltage from no-load to full-load conditions.

• A. 100 V/cm
• B. 6 V/cm
• C. 1000 V/cm
• D. More than 105 V/cm

Explanation: A semiconductor's covalent bonds are broken by a very strong electric field, typically exceeding 10^5 V/cm.

• A. c. voltage regulator only
• B. c. voltage regulator only
• C. both D.C and A.C voltage regulator
• D. none of the above

Explanation: A zener diode operates in reverse breakdown to maintain an approximately constant voltage, and suitable circuits can regulate rectified DC…

• A. Soft magnetic materials
• B. Hard magnetic materials
• C. Either A. or B.
• D. None of the above

Explanation: Soft magnetic materials are used for electromagnet cores because they magnetize readily and lose their magnetism when the magnetizing…

• A. conductors
• B. semiconductors
• C. insulators
• D. superconductors

Explanation: A superconductor has zero electrical resistivity below its critical temperature, so it can carry current without ohmic power loss.

• A. forward biasing voltage
• B. reverse biasing voltage
• C. temperature
• D. the amount of doping

Explanation: Minority-carrier concentration changes strongly with temperature because the intrinsic carrier concentration increases rapidly as…

• A. equal to
• B. less than
• C. greater than
• D. any of the above

Explanation: For the same electric field in an intrinsic semiconductor, electron and hole concentrations are equal, but electron mobility is higher…

• A. 0.15 eV
• B. 0.25 eV
• C. 0.5eV
• D. 0.7eV

Explanation: Germanium has a forbidden energy gap of about 0.67 eV at room temperature, commonly rounded to 0.7 eV.

• A. An acceptor
• B. A donor
• C. Germanium
• D. Silicon

Explanation: A trivalent impurity has three valence electrons and creates a hole when added to a semiconductor, so it is called an acceptor.

• A. low carbon steel
• B. wrought iron
• C. cast iron
• D. malleable iron

Explanation: Wrought iron contains very little carbon, typically below about 0.%C, whereas low-carbon steel contains more and cast iron contains much…

• A. Holes can exist in certain semiconductors only
• B. Holes can exist in any material including conductors
• C. Holes may constitute an electric current
• D. Holes can be considered as a net positive charge

Explanation: A hole is the effective positive charge produced by a missing electron in a semiconductor crystal and can contribute to current.

• A. zero
• B. one
• C. negative
• D. more than one

Explanation: A superconductor expels magnetic flux in the Meissner state and behaves as a perfect diamagnet.

• A. Age hardening
• B. Alloying
• C. Temperature
• D. Cold work
• E. All of the above

Explanation: All listed factors can alter metallic resistivity: alloying and cold work introduce scattering, temperature changes lattice vibrations…

• A. large
• B. small
• C. nil
• D. any of the above

Explanation: Insulators have a large forbidden energy gap, so electrons need substantial energy to move from the valence band to the conduction band.

• A. extrnisic
• B. intmisic
• C. N-type
• D. P-type

Explanation: Pure selenium is classified as an intrinsic semiconductor because its conductivity arises from the material itself rather than from…

• A. intensity
• B. speed
• C. frequency
• D. wave length

Explanation: Photoelectric emission requires the incident light frequency to exceed a threshold frequency determined by the material's work function.

• A. Phosphorous
• B. Rubber
• C. Silicon
• D. Aluminium

Explanation: Silicon is a group-IV elemental semiconductor whose conductivity lies between that of conductors and insulators.

• A. positive ions only
• B. negative ions only
• C. positive and negative ions
• D. electrons and holes

Explanation: Semiconductor current is carried by both negatively charged electrons and positively charged holes.

• A. Solubility
• B. Viscosity
• C. Porosity
• D. Hygroscopicity

Explanation: Hygroscopicity is the tendency of a material to absorb moisture from the surrounding atmosphere.