Digital & Industrial Electronics MCQs – DAE Electrical Engineering 50 Score: 0 Attempted: 0/50 1. A digital signal has: (A) Discrete levels of voltage (B) Continuous voltage (C) Random noise (D) Sinusoidal waveformShow All Answers 2. The main advantage of digital electronics over analog is: (A) High voltage only (B) Noise immunity and accuracy (C) High current only (D) Low frequency 3. A logic “1” in digital circuits represents: (A) High voltage level (B) Low voltage level (C) Zero voltage (D) Negative voltage 4. The binary number system uses: (A) 0 and 1 (B) 0, 1, 2 (C) 0,1,2,3 (D) 1–10 5. The decimal equivalent of binary 1011 is: (A) 13 (B) 12 (C) 10 (D) 11 6. A NOT gate is also called: (A) Inverter (B) AND gate (C) OR gate (D) NAND gate 7. The output of an AND gate is “1” only when: (A) All inputs are “1” (B) Any input is “1” (C) All inputs are “0” (D) Only first input is “1” 8. The output of an OR gate is “1” when: (A) All inputs are “1” (B) All inputs are “0” (C) Any input is “1” (D) First input is “0” 9. A NAND gate is equivalent to: (A) AND gate followed by NOT (B) OR gate (C) NOR gate (D) XOR gate 10. A flip-flop is used to: (A) Generate AC (B) Amplify signals (C) Store a single bit of data (D) Convert DC to AC 11. A D flip-flop stores: (A) Data at the clock edge (B) Always 0 (C) Always 1 (D) Sum of inputs 12. A JK flip-flop differs from a SR flip-flop because: (A) It does not have an invalid state (B) It has more outputs (C) It is analog (D) It cannot toggle 13. The main function of a counter is to: (A) Generate sinusoidal signal (B) Store voltage (C) Switch current (D) Count pulses or events 14. A 4-bit binary counter can count up to: (A) 15 (B) 16 (C) 8 (D) 10 15. A multiplexer (MUX) is used to: (A) Generate pulses (B) Store data (C) Amplify voltage (D) Select one input from many and forward it to output 16. A demultiplexer (DEMUX) is used to: (A) Route a single input to one of many outputs (B) Store bits (C) Convert AC to DC (D) Amplify signals 17. An ADC (Analog to Digital Converter) converts: (A) Analog signals to digital signals (B) Digital to analog (C) AC to DC (D) Voltage to current 18. A DAC (Digital to Analog Converter) converts: (A) Analog to digital (B) Digital signals to analog signals (C) AC to DC (D) High voltage to low voltage 19. Industrial electronics commonly uses: (A) Sensors, PLCs, and drives (B) Only resistors and capacitors (C) Only transformers (D) Only batteries 20. A PLC (Programmable Logic Controller) is used for: (A) Automating industrial processes (B) Generating AC (C) Converting DC to AC (D) Measuring voltage only 21. A TRIAC is used in: (A) Transformers (B) DC generation (C) AC switching and control (D) Relays 22. A SCR (Silicon Controlled Rectifier) is used for: (A) Controlled rectification (B) Signal amplification (C) Voltage step-up (D) Frequency change 23. In industrial drives, speed control is achieved by: (A) Changing conductor size (B) Varying supply voltage or frequency (C) Changing insulation (D) Changing resistance only 24. A common sensor used in industrial automation is: (A) Proximity sensor (B) Fuse (C) Switch (D) Resistor 25. TTL logic gates operate at: (A) 220 V (B) 12 V (C) 24 V (D) 5 V 26. CMOS logic gates are preferred because: (A) Low power consumption (B) High voltage only (C) High current only (D) Fast AC switching 27. In digital electronics, a clock signal is used to: (A) Step up voltage (B) Supply power (C) Synchronize operations of circuits (D) Reduce current 28. A buffer gate is used to: (A) Strengthen signal without changing logic (B) Invert signal (C) Convert analog to digital (D) Store data 29. A Schmitt trigger is used to: (A) Store data (B) Generate sinusoidal signal (C) Eliminate noise from digital signals (D) Amplify current 30. A binary half adder adds: (A) Two single-bit numbers (B) Three numbers (C) Only carry (D) Only sum 31. A full adder adds: (A) Only two bits (B) Two bits and a carry input (C) Only sum (D) Only carry 32. Inverters are widely used in: (A) DC-AC conversion (B) AC-DC conversion (C) Step-up transformers (D) Motors only 33. Industrial electronics improves: (A) Efficiency and control of machines (B) Voltage only (C) Frequency only (D) Load only 34. Industrial drives use: (A) Only switches (B) Only resistors (C) Only transformers (D) DC drives, AC drives, and VFDs 35. A relay in industrial electronics is used to: (A) Switch loads electrically (B) Step up voltage (C) Reduce current (D) Store energy 36. The main purpose of industrial control panels is: (A) Increase frequency (B) Step up voltage (C) Step down current (D) Safe and centralized control of machinery 37. A PLC input can be: (A) Digital or analog (B) Only voltage (C) Only current (D) Only resistive 38. A PLC output can be: (A) Only digital (B) Digital, analog, or relay operated (C) Only analog (D) Only relay 39. Digital electronics use: (A) Logic levels to represent data (B) Continuous voltage only (C) AC signals only (D) DC signals only 40. Industrial sensors convert physical quantity into: (A) Chemical signals (B) Mechanical signals (C) Electrical signals (D) Thermal signals 41. H-bridge circuits are used to: (A) Control direction of DC motors (B) Measure voltage (C) Measure current (D) Step up AC 42. Logic families include: (A) Resistor, capacitor (B) AC, DC only (C) TTL, CMOS, ECL (D) Transformer only 43. Industrial electronics reduces: (A) Human intervention in repetitive processes (B) Voltage (C) Current (D) Frequency 44. A SCR gate turn-off requires: (A) Increase of current (B) Increase of voltage (C) Reduction of current below holding current (D) AC input only 45. Opto-isolators are used for: (A) Electrical isolation between circuits (B) Power conversion (C) Voltage amplification (D) Frequency modulation 46. A bistable multivibrator is: (A) Counter (B) Oscillator (C) Amplifier (D) Flip-flop storing one bit 47. Industrial electronics controllers improve: (A) Accuracy and repeatability (B) Voltage only (C) Frequency only (D) Load only 48. A logic XOR gate output is “1” when: (A) All inputs “1” (B) Inputs are same (C) All inputs “0” (D) Inputs are different 49. Digital timers in industrial circuits are used for: (A) Delayed operations (B) Voltage step-up (C) Load monitoring only (D) Frequency measurement 50. PLC programming languages include: (A) Only Java (B) Only C programming (C) Ladder logic, function block, structured text (D) Only Python