BSc Physics SEM VI 2018 19 May 2018-19 PHYSICS ELECTRONICS Question Paper - Mumbai University | munotes

Questions asked in this paper

• (2) Figures to the right indicate full marks

1. Q1 Attempt any two:
   • (1) Explain JFET as multiplexer and voltage controlled resistor. 10 Sketch the cross section of Depletion MOSFET and Enhancement MOSFET. 10 Explain the use of MOSFET to drive passive and active load
   • (iii) Explain the use of SCR as half wave rectifier and derive the expression for its 10 average output voltage and current
2. Q2 Attempt any two:
   • (1) Draw a neat circuit diagram of the basic configuration of instrumentation 10 amplifier using three operational amplifiers. Explain its working and derive an expression for its voltage gain With the help of a neat circuit diagram, explain the working of triangular wave 10 generator using Schmitt trigger and integrator. Sketch the waveforms at output terminals of Schmitt trigger and. integrator. What is the expression for frequency and peak to peak voltage of the triangular wave?
   • (iii) is Differential Amplifier? Explain with neat circuit diagram the working 10 of an emitter coupled differential amplifier with single ended input and double
3. Q3 Attempt any two:
   • (1) Draw a neat circuit diagram of a transistorized astable multivibrator. With the 10 help of necessary waveforms explain its working and derive an expression for frequency of output wave
   • (ii) Draw the circuit diagram of IC 555 to work as monostable multivibrator. 10 Explain its operation and sketch the relevant waveforms. Obtain expression for the output pulse width
   • (iii) With the help neat circuit diagram, explain the working of series voltage 10 feedback regulator. Derive an expression for its output voltage and power
4. Q4 Attempt any two:
   • (i) Explain the working of two inputs CMOS NAND gate with neat diagram and 10
   • (ii) are the benefits of digital communication? Explain the benefits with 10 necessary diagrams. What are the disadvantages of digital communication?
   • (iii). is pulse modulation? Explain PAM, PWM and PPM. 10
5. Q5 Attempt any four:---(5 marks each) 20 marks
   • (i) The intrinsic stand-off ratio for a UJT is determined to be 0.6. If the inter-base resistance is 10 KQ, what are the values of and Rp2?
   • (ii) Calculate the operating point for the fixed bias n-channel JFET circuit with
   • (iii) amplifier with double ended input and single ended output circuit Re = 47 KQ. The left silicon transistor has Bac = 100 and the right silicon transistor has Bac = 120. If V for silicon transistor and What are the dc base currents in each silicon transistor? Calculate the input offset current and the input bias current
   • (iv) First order active low pass filter has C = and R= Calculate cut-off frequency. If Rr is 1kQ and R; is 1kQ, calculate pass band gain. What will be the gain at cut-off frequency?
   • (v) A pulse width modulator using IC 555 has Vee =12V , R = 9.1kQ and C = . The clock has frequency of 2.5 kHz. If a modulating signal has peak value of 2V, what is the period of the output pulse? What are the minimum and maximum pulse widths?
   • (vi) Draw a neat circuit diagram LM317 three terminal voltage regulator to obtain adjustable supply. Design the regulated voltage source using LM 317 so that its output voltage Vo = 9V and the minimum current through it is 5 mA (vit) Explain CMOS inverter with neat diagram Draw neat diagram of TTL NOR gate. and write its truth table

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