Quiz — MPY351

Q1. The forward-bias diode current is best described by:

A. I = I0(exp(V/ηVT) - 1) B. I = V/R only (Ohm's law) C. I = constant regardless of voltage D. I decreases exponentially with voltage

Q2. The 'cut-in' or 'threshold' voltage of a silicon diode is approximately:

A. 0.1 V B. 0.6-0.7 V C. 2 V D. 5 V

Q3. Reverse saturation current in a diode is:

A. Very large and increases linearly with voltage B. Very small and nearly constant until breakdown C. Exactly zero always D. Equal to the forward current

Q4. Static resistance of a diode at an operating point is calculated as:

A. ΔV/ΔI B. V/I at that point C. dI/dV D. I × V

Q5. Dynamic (AC) resistance of a diode is obtained from:

A. The slope of the V-I curve (ΔV/ΔI) at the operating point B. The total voltage divided by total current C. The diode's physical dimensions only D. The ambient temperature only

Q6. In CE configuration, BJT input characteristics are plotted as:

A. IC vs VCE B. IB vs VBE at constant VCE C. IE vs VCB D. IC vs IB only

Q7. In CE configuration, BJT output characteristics are plotted as:

A. IB vs VBE B. IC vs VCE for various fixed IB C. IE vs VBE D. VCE vs VBE

Q8. Current gain β of a BJT is defined as:

A. ΔIC/ΔIB B. ΔIB/ΔIC C. IE/IC D. VCE/IC

Q9. The three operating regions visible in BJT output characteristics are:

A. Only active and cut-off B. Active, saturation and cut-off C. Only saturation and breakdown D. Linear, quadratic and cubic

Q10. FET drain characteristics plot:

A. ID vs VDS at fixed VGS B. VGS vs ID at fixed VDS C. IG vs VDS D. VDS vs VGS only

Q11. FET transfer characteristics plot:

A. ID vs VGS at fixed VDS B. ID vs VDS at fixed VGS C. VGS vs VDS D. IG vs ID

Q12. Pinch-off voltage VP of a FET is extracted from:

A. The output characteristics only B. The transfer characteristics curve C. The gate leakage current D. The supply voltage rating

Q13. MOSFET differs from JFET mainly because its gate is:

A. Directly connected to the channel B. Insulated from the channel by an oxide layer C. Made of a different semiconductor entirely D. Absent

Q14. Enhancement-mode MOSFET conducts when:

A. VGS is below threshold voltage B. VGS exceeds a positive threshold voltage (for n-channel) C. No gate voltage is applied D. The drain is grounded

Q15. A Colpitts oscillator uses a feedback network consisting of:

A. A tapped inductive divider with one capacitor B. A tapped capacitive divider (two capacitors) with one inductor C. Only resistors D. A single diode

Q16. The oscillation frequency of a Colpitts oscillator is given by:

A. f = 1/(2π√(L Ceq)) B. f = 2πLC C. f = RC D. f = 1/(RC)

Q17. A Hartley oscillator uses:

A. A tapped capacitive divider with one inductor B. A tapped inductive divider (two inductors) with one capacitor C. Only an op-amp with no reactive components D. A Zener diode as the feedback element

Q18. Compared to Colpitts, the Hartley oscillator is best described as its:

A. Identical circuit with a different name B. Dual, with inductors and capacitors interchanged in role C. Unrelated circuit topology D. A digital circuit variant

Q19. A phototransistor differs from a photodiode in that it:

A. Has no light sensitivity B. Provides internal current gain, giving higher sensitivity C. Only works in darkness D. Cannot be used in fibre-optic links

Q20. In a phototransistor characteristic curve, the controlling parameter (replacing base current) is:

A. Supply voltage B. Illumination level (light intensity) C. Ambient temperature only D. Collector resistance

Q21. A basic fibre-optic communication experiment typically uses which transmitter device?

A. A microphone B. An LED or laser diode C. A thermocouple D. A photoresistor

Q22. A positive clipper circuit removes:

A. The negative portion of a waveform B. The positive portion of a waveform above a reference level C. The entire waveform D. Only the DC component

Q23. A biased clipper circuit differs from a simple clipper by:

A. Having no diode at all B. Clipping at an adjustable reference level set by a battery/potential divider C. Clipping only at zero volts D. Removing all AC components

Q24. A clamper circuit is used to:

A. Remove part of a waveform B. Shift a waveform's DC level without changing its shape C. Amplify a waveform's frequency D. Convert AC to DC completely

Q25. A clamper circuit typically consists of:

A. Only a resistor B. A diode and a capacitor C. Two inductors D. An op-amp only

Q26. A Wien-bridge oscillator using an op-amp (IC 741) produces:

A. A square wave B. A sine wave with frequency f = 1/(2πRC) C. A sawtooth wave only D. No output at all

Q27. The frequency-determining components of a Wien-bridge oscillator are:

A. Only capacitors B. Resistors and capacitors (RC network) C. Only inductors D. Only diodes

Q28. In astable mode, a 555 timer IC behaves as a:

A. One-shot pulse generator B. Free-running square-wave generator C. Fixed voltage regulator D. Amplifier only

Q29. In monostable mode, a 555 timer produces:

A. A continuous square wave B. A single output pulse of duration T = 1.1RC when triggered C. No output ever D. A sine wave

Q30. The 555 timer's monostable pulse duration formula is:

A. T = RC B. T = 1.1RC C. T = 2πRC D. T = R/C

Q31. A CRO (cathode ray oscilloscope) is primarily used in these experiments to:

A. Measure resistance directly B. Observe and measure waveforms, frequency and amplitude C. Generate DC voltage D. Amplify signals only

Q32. A function generator in this lab is typically used to:

A. Measure current only B. Supply test input signals (sine/square/triangular) to circuits under test C. Replace the multimeter entirely D. Store lab data

Q33. The purpose of a regulated power supply in these experiments is to:

A. Provide stable, adjustable DC bias voltages to circuits B. Generate AC signals only C. Measure resistance D. Replace the CRO

Q34. Ge diodes typically have a lower cut-in voltage than Si diodes because:

A. Ge has a smaller energy band gap than Si B. Ge has a larger band gap than Si C. Ge conducts only in reverse bias D. Si has no band gap

Q35. A multivibrator circuit is generally used to generate:

A. Only DC voltages B. Rectangular/pulse waveforms (astable, monostable or bistable) C. Pure sine waves only D. No output signal

Q36. An astable multivibrator has:

A. Two stable states B. No stable state; it free-runs between two quasi-stable states C. One stable and one quasi-stable state D. Infinite stable states

Q37. A monostable multivibrator has:

A. No stable state B. One stable state and one quasi-stable (triggered) state C. Two stable states only D. Continuous free-running output

Q38. The main advantage of using breadboard prototyping in this lab is:

A. Permanent, unmodifiable connections B. Quick, solder-free assembly and testing of circuits C. Higher power handling than a PCB D. Immunity to all wiring errors

Q39. If a diode is connected in reverse bias beyond its breakdown voltage, the current:

A. Remains negligible indefinitely B. Increases sharply (avalanche/Zener breakdown) C. Becomes exactly zero D. Reverses sign of voltage

Q40. For accurate BJT characteristic curves, base current IB should be:

A. Left uncontrolled B. Set and held at fixed known values while varying VCE C. Measured only after removing all resistors D. Ignored entirely

Q41. The transfer characteristic curve of a FET helps determine:

A. Supply voltage rating only B. Pinch-off voltage VP and saturation drain current IDSS C. The diode's cut-in voltage D. BJT current gain

Q42. Which instrument is essential for accurately measuring oscillation frequency in the Colpitts/Hartley oscillator experiments?

A. Ohmmeter B. CRO / frequency counter C. Barometer D. Ammeter alone

Q43. A key precaution while testing a MOSFET in the lab is to:

A. Handle it without any ESD (electrostatic discharge) precautions B. Avoid electrostatic discharge, since the gate oxide can be damaged by static charge C. Apply reverse voltage far beyond ratings intentionally D. Submerge it in water

Q44. The 555 timer IC is generally classified as:

A. A purely digital logic gate B. A versatile analog-digital timer/oscillator IC C. A type of diode D. A capacitor

Q45. In an experiment on clipper circuits, changing the bias voltage mainly affects:

A. The frequency of the input signal B. The level at which the waveform is clipped C. The colour of the LED indicator D. The resistance of the diode permanently

Q46. A key design equation used to calculate the 555 astable frequency is based on:

A. Only the supply voltage B. The charging/discharging time constants set by two resistors and a capacitor C. The diode's cut-in voltage D. The BJT's current gain

Q47. Fibre-optic link experiments in this lab primarily demonstrate:

A. Wireless radio transmission B. Optical transmission of a signal via LED/laser diode, fibre, and photodetector C. Only analog audio amplification D. High-voltage power transmission

Q48. For a clean sine wave output, the Wien-bridge oscillator circuit typically also requires:

A. No amplification at all B. An amplitude-stabilization mechanism (e.g., a lamp or diode limiter) alongside the op-amp gain C. A square-wave input only D. A diode clipper on the output always

Q49. Which of the following is NOT typically an experiment listed in the MPY351 Electronics Lab syllabus?

A. Diode characteristics B. Hartley oscillator C. Determination of Planck's constant using LEDs D. 555 timer experiments

Q50. A key advantage of the FET over the BJT, relevant to circuit design choices in this lab, is its:

A. Lower input impedance B. Very high input impedance, drawing negligible gate current C. Larger physical size D. Inability to amplify signals

MPY35150-Question MCQ Quiz