Electronic Circuits I - Tutoril 03 Diode Applictions I -1 / 9 -
T & F # Question 1 A diode cn conduct current in two directions with equl ese. F 2 When reverse-bised, diode idelly ppers s short. F 3 A bsic hlf-wve rectifier consists of one diode. T 4 The diode in hlf-wve rectifier conducts for hlf the input cycle. T 5 Ech diode in full-wve rectifier conducts for the entire input cycle. F MCQ1 # Question 1 When diode is forwrd-bised nd the bis voltge is incresed, the forwrd current will 2 When diode is reverse-bised nd the bis voltge is incresed, the reverse current (ssuming the prcticl model) will 3 When diode is forwrd-bised nd the bis voltge is incresed, the voltge cross the diode (ssuming the complete model) will 4 If the forwrd current in diode is decresed, the diode voltge (ssuming the complete model) will 5 If the input voltge in Figure 2 28 is incresed, the pek inverse voltge cross the diode will c b A -2 / 9 -
6 If the frequency of the input voltge in Figure 2 36 is incresed, the output voltge will c MCQ 2 # Question Answer 1 1. The term bis mens c () the rtio of mjority crriers to minority crriers (b) the mount of current cross diode (c) dc voltge is pplied to control the opertion of device (d) neither (), (b), nor (c) 2 When diode is forwrd-bised, d () the only current is hole current (b) the only current is electron current (c) the only current is produced by mjority crriers (d) the current is produced by both holes nd electrons 3 For silicon diode, the vlue of the forwrd-bis voltge typiclly b () must be greter thn 0.3 V (b) must be greter thn 0.7 V (c) depends on the width of the depletion region (d) depends on the concentrtion of mjority crriers 4 A diode is normlly operted in d () reverse brekdown (b) the forwrd-bis region (c) the reverse-bis region (d) either (b) or (c) 5 The V-I curve for diode shows () the voltge cross the diode for given current (b) the mount of current for given bis voltge (c) the power dissiption (d) none of these 6 In the prcticl diode model, () the brrier potentil is tken into ccount -3 / 9 -
(b) the forwrd dynmic resistnce is tken into ccount (c) none of these (d) both () nd (b) 7 The verge vlue of hlf-wve rectified voltge with pek vlue of 200 V is () 63.7 V (b) 127.2 V (c) 141 V (d) 0 V 8 The pek vlue of the input to hlf-wve rectifier is 10 V. The pproximte pek vlue of the output is () 10 V (b) 3.18 V (c) 10.7 V (d) 9.3 V 7 The verge vlue of full-wve rectified voltge with pek vlue of 75 V is () 53 V (b) 47.8 V (c) 37.5 V (d) 23.9 V 8 The totl secondry voltge in center-tpped full-wve rectifier is 125 V rms. Neglecting the diode drop, the rms output voltge is () 125 V (b) 177 V (c) 100 V (d) 62.5 V D b d Problems Problem 1 Assume tht the diode in Figure 2 18() fils open. Wht is the voltge cross the diode nd the voltge cross the limiting resistor? Answer 1 Vd=10V, VRlimit-0; -4 / 9 -
Problem 2 Determine the verge vlue of the hlf-wve voltge if its pek mplitude is 12 V. Answer 2 3.82 V Proble m 3 Answer 3 Q4 To forwrd-bis diode, to which region must the positive terminl of voltge source be connected? 4 p region -5 / 9 -
Q5 Explin how to generte the forwrd-bis portion of the chrcteristic curve. 5 To generte the forwrd bis portion of the chrcteristic curve, connect voltge source cross the diode for forwrd bis nd plce n mmeter in series with the diode nd voltmeter cross the diode. Slowly increse the voltge from zero nd plot the forwrd voltge versus the current. Q6 Drw the output voltge wveform for ech circuit in Figure nd include the voltge vlues 6-6 / 9 -
Q7 Clculte the verge vlue of hlf-wve rectified voltge with pek vlue of 200 V. 7 63.7 V Problem 8 Wht diode PIV rting is required to hndle pek input of 160 V in Figure 2 36? Answer 8 79.3 V including diode drop Q9 9 A power-supply trnsformer hs turns rtio of 5:1. Wht is the secondry voltge if the primry is connected to 120 V rms source? 24 V rms -7 / 9 -
Q01 Find the verge vlue of ech voltge in Figure 01 () 1.59 V (b) 63.7 V (c) 16.4 V (d) 10.5 V -8 / 9 -
Q00 Clculte the pek voltge cross ech hlf of center-tpped trnsformer used in full-wve rectifier tht hs n verge output voltge of 120 V. 00 186 V -9 / 9 -