Free Electronics and Devices MCQs with Answers

• A. tubes
• B. rolled foil
• C. disc
• D. meshed plates

Explanation: Paper capacitors commonly use paper dielectric layers wound between metal foils, giving them a rolled-foil construction.

• A. Air capacitor
• B. Ceramic capacitor
• C. Paper capacitor
• D. None of the above

Explanation: Ceramic capacitors are available with controlled temperature coefficients, including negative coefficients, so they can offset…

• A. zero
• B. 1
• C. 4
• D. 10

Explanation: The dielectric constant, or relative permittivity, is defined as the material permittivity divided by the permittivity of free space.

• A. scalar
• B. vector
• C. both A. and (6)
• D. none of the above

Explanation: Electric field intensity has both magnitude and direction, with its direction defined as the force on a positive test charge.

• A. 200
• B. 100
• C. 3 to 8
• D. 1 to 2

Explanation: Mica has a relative permittivity typically in the range of about 3 to 8.

• A. air capacitor
• B. mica capacitor
• C. electrolytic capacitor
• D. none of the above

Explanation: Mica capacitors are valued in high-frequency circuits because mica has low dielectric loss, good stability, and small leakage.

• A. Ceramics
• B. Oil
• C. Glass
• D. Paper

Explanation: Oil has a relative permittivity of roughly 2 to 3, which is lower than typical paper, glass, and ceramic materials.

• A. Paper capacitor
• B. Mica capacitor
• C. Ceramic disc capacitor
• D. None of the above

Explanation: Mica capacitors are preferred where close tolerance is needed because mica is mechanically stable and has a highly uniform dielectric.

• A. ± 5%
• B. ± 10%
• C. ± 15%
• D. ± 20%Civil Engineering

Explanation: Paper capacitors commonly have a tolerance of about ±10%, although older or lower-grade types may have wider tolerances.

• A. Air
• B. Paper
• C. Mica
• D. Electrolytic

Explanation: Electrolytic capacitors are polarized, so they must be connected with the correct DC polarity and cannot normally be used with reversed or…

• A. 0.1 to 0.4
• B. 0.5 to 1.0
• C. 2.0 to 4.0
• D. 5 to 100Educational Resources

Explanation: Glass generally has a relative permittivity of about 5 to 10, although its value varies considerably with composition.

• A. 10 to 20 kV/mm
• B. 30 to 50 kV/mm
• C. 50 to 200 kV/mm
• D. 300 to 500 kV/mmElectricity

Explanation: Mica is valued as an insulating dielectric because it has high dielectric strength, commonly about 50 to 200 kV/mm.

• A. Paper
• B. Air
• C. Mica
• D. Electrolytic

Explanation: Air capacitors, especially variable types, have low losses and stable performance at high frequency, making them suitable for radio…

• A. V/m
• B. V2/m
• C. m/V
• D. m/V2

Explanation: Dielectric strength is the maximum electric field an insulating material can withstand before breakdown, so its unit is volt per metre…

• A. scalar
• B. vector
• C. both of the above
• D. none of the above

Explanation: Electric displacement D has both magnitude and direction, with D = εE, so it is a vector quantity.

• A. Paraffin wax
• B. Quartz
• C. Glass
• D. Air

Explanation: Among these materials, air has the lowest dielectric strength, approximately 3 kV/mm under standard conditions.

• A. Farad/sq-m
• B. Farad/meter
• C. Weber/meter
• D. Weber/sq-m

Explanation: Permittivity is capacitance per unit geometry and has the SI unit farad per metre (F/m). Farad per square metre is not its SI unit.

• A. capacitance
• B. charge
• C. energy
• D. none of the above

Explanation: Capacitance is the property that determines how much charge a capacitor stores for a given voltage, C = Q/V.

• A. moisture content
• B. temperature
• C. thickness
• D. all of the above
• E. none of the above

Explanation: Dielectric strength varies with moisture, temperature, and specimen thickness, because each affects insulation breakdown behavior.

• A. shorter plate area and higher applied voltage
• B. shorter plate area and shorter distance between them
• C. larger plate area, longer distance between plates and higher,applied voltage
• D. larger plate area and shorter distance between plates

Explanation: For parallel plates, C = εA/d, so capacitance increases with plate area and decreases when the separation is reduced.