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1. Which of the following is not known as transition capacitance
a) Junction capacitance
b) Space-Charge capacitance
c) Diffusion capacitance
d) Barrier capacitance

Answer: c [Reason:] Transition capacitance is the capacitance exhibited by a diode due to the p-side and n-side of the diode is separated by a distance of depletion width same as in an electrolytic capacitor. The other names for this is Junction capacitance, Space-Charge capacitance, Barrier capacitance, Depletion region capacitance.

2. Which of the following is not known as transition capacitance
a) Depletion region capacitance
b) Space-Charge capacitance
c) Nominal capacitance
d) Junction capacitance

Answer: c [Reason:] Transition capacitance is the capacitance exhibited by a diode due to the p-side and n-side of the diode is separated by a distance of depletion width same as in an electrolytic capacitor. The other names for this is Junction capacitance, Space-Charge capacitance, Barrier capacitance, Depletion region capacitance.

3. Transition capacitance of a diode is directly proportional to
a) Area of cross section
b) Width of depletion region
c) Reverse voltage applied across the terminals
d) Drift current

Answer: a [Reason:] Transition capacitance is the capacitance exhibited by a diode due to the p-side and n-side of the diode is separated by a distance of depletion width same as in an electrolytic capacitor. The equation of transition capacitance = ƸA/W Where Ƹ = permittivity of the material of diode , W = depletion width A = area of cross section.

4. Transition capacitance of a diode is inversely proportional to
a) Area of cross section
b) Width of depletion region
c) Relative permittivity
d) Drift current

Answer: b [Reason:] Transition capacitance is the capacitance exhibited by a diode due to the p-side and n-side of the diode is separated by a distance of depletion width same as in an electrolytic capacitor. The equation of transition capacitance = ƸA/W Where Ƹ = permittivity of the material of diode , W = depletion width A = area of cross section.

5. As reverse bias voltage increases transition capacitance
a) Increases
b) Decreases
c) Doesn’t depend upon voltage
d) constant

Answer: b [Reason:] Transition capacitance is the capacitance exhibited by a diode due to the p-side and n-side of the diode is separated by a distance of depletion width same as in an electrolytic capacitor. The equation of transition capacitance = ƸA/W Where Ƹ = permittivity of the material of diode , W = depletion width A = area of cross section As reverse bias increases depletion width also increases hence transition capacitance decreases.

6. Relation between relative permittivity and transition capacitance is, they are
a) Inversely proportional
b) Directly proportional
c) Independent
d) Directly proportional with degree 2.

Answer: b [Reason:] Transition capacitance is the capacitance exhibited by a diode due to the p-side and n-side of the diode is separated by a distance of depletion width same as in an electrolytic capacitor. The equation of transition capacitance = ƸA/W Where Ƹ = permittivity of the material of diode , W = depletion width A = area of cross section Relative permittivity is directly proportional to permittivity of material.

7. For a diode the transition capacitance was 10pF. The depletion width changed from 1µm to 10 µm. All other conditions remain unchanged. The new diode capacitance is
a) 5pF
b) 1.414pF
c) 1pF
d) 10pF

Answer: c [Reason:] The equation of transition capacitance = ƸA/W Where Ƹ = permittivity of the material of diode , W = depletion width A = area of cross section Since depletion width increased 10 times and all other quantities are same, the capacitance decrease by 10 times.

8. For a diode the transition capacitance was 15pF. The diode is replaced with another diode of same material with twice cross sectional area. Terminal voltage remains unchanged. The capacitance of new diode is
a) 15pF
b) 30pF
c) 60pF
d) 7.5pF

Answer: b [Reason:] The equation of transition capacitance = ƸA/W Where Ƹ = permittivity of the material of diode , W = depletion width A = area of cross section Since A becomes 2A capacitance also doubles.

9. A diode is replaced with another diode of different material. The ratio of relative permittivity of new material to old is 0.5. The initial capacitance was 20pF, then final capacitance will be
a) 15pF
b) 20pF
c) 10pF
d) 2pF