BED IMPORTANT QUESTIONS


1)      (a) Define Drift and Diffusion currents with necessary expressions?
(b) Derive the Continuity Equation with necessary Diagrams?
(c)  An N-Type semiconductor has Hall coefficient of 200 cm3/C and its conductivity is 10 S/m, find its mobility?
2)   Write short notes on
          a) Light Emitting Diode           b) Varactor Diode
          c) Photo Diode                         d)   PiN diode
3) (a)A half wave rectifier, having a resistance load of 325V peak value and diode has a forward        resistance of 100Ω. Calculate (1) peak, average, rms value of current (2) de power output                        (3) ac   input power (4) efficiency
    (b) Draw the series voltage regulator and explain its operation?




1)      (a)What is Hall Effect? Derive the hall voltage expression with necessary diagrams?
     (b) Explain Fermi Dirac function with neat diagrams and expressions?

 2) (a) Derive the diode current equation and how this expression relating the Voltage (V) and                  current(I)?
(b) Explain with help of neat diagram different regions in the zener diode characteristics?
(c) Explain avalanche and zener break down mechanisms?

2)        (a) Draw the output wave form of a capacitor filter and derive the expression for ripple factor                        which is connected to a full wave rectifier?
 (b) Calculate the value of capacitance to use in a capacitor filter connected to a full wave rectifier operating at a standard frequency of 400 Hz, if the ripple factor is 10% for a load of 500Ω?
                                  



1)      (a) Define Fermi energy level? Explain energy band structures of different materials? 
(b) The mobility of free electrons and holes in pure Germanium material are 3800 and 1800 Cm2/v-s.The corresponding values for pure silicon are 1300 and 500 cm2/v-s. determine        values of intrinsic and extrinsic conductivity of Ge,Si when ni = 2.5X1013 cm-3for Ge , ni = 1.5X1010cm-3for Si
2)      (a) What type of capacitance existed in diode forward bias condition? Derive the capacitance       equation?
 (b) Find the voltage at which the reverse current in a Ge PN Junction diode attains in a value of 90% of its saturation value at room temperature?

3)      (a)  230 v, 60 Hz voltage is applied to the primary of a 5:1 step-down, center tap transformer used in  a full wave rectifier having load 900 Ω. If the diode resistance and secondary coil resistance together has a resistance of 100Ω , determine (a)D.C voltage across the load (b) D.C current flowing through the load (c) D.C power delivered to the load (d) PIV of each diode (e) ripple voltage.
(b) Compare half wave rectifier and Full wave rectifier in terms of all specifications?  

               

1)      (a) Find the conductivity of silicon (1)in intrinsic condition at room temperature of 300K  (2) with   donor impurity of 1 in 108  (3) with acceptor impurity of 1 in 5X107(4)with both impurities present simultaneously , Given ni for silicon at 300K is 1.5X1010 cm-3 , μn= 1300 cm2/v-s,μp = 500 cm2/v-s, number of silicon atoms per cm3= 5X1022.
(b) What is “mean carrier lifetime” of a charge carrier and Explain generation and recombination of charge carriers with necessary expressions in semiconductor materials?

2)      (a) Explain Fermi energy level in a PN diode with neat diagrams and derive the expression for Barrier potential?
(b) Explain, why there is a negative resistance region in tunnel diode characteristics?

3)      (a)Draw the circuit diagram of Full-wave rectifier and derive the necessary expressions (a) Ripple factor (b) Vdc (c) Vrms  (d) PIV (e) T.U.F (d) Efficiency   (f) Form Factor (g) Peak Factor
(b) Derive the expression for ripple factor of inductor filter connected to a full wave rectifier and draw the circuit diagram?



BED IMPORTANT QUESTIONS BED IMPORTANT QUESTIONS Reviewed by Suresh Bojja on 9/22/2015 08:50:00 AM Rating: 5

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