Semi Conductors Objectives Part 09

161 . The reverse resistance of a PN-junction diode is given by Break down voltage/reverse leakage current.

162 . The depletion layer of PN-junction diode has neither free mobile electrons nor holes.

163 . With the rise in temperature of a PN junction, reverse leakage current will increase.

164 . For a PN-junction we have width of depletion layer and junction barrier voltage.

165 . A zener diode is invariably used with reverse bias.

166 . The temperature coefficient is positive in case extrinsic semiconductor. 167.

167 . A light emitting diode produces light when forward bias.

Questions 168 and 169 refer to Fig.16
The voltage wave form resulting from a three phase half wave rectifier is shown in Fig.16

168 . The average value of voltage is 82.7V.

169 . Therms value is 84V.
Question 170 to 173 refer to Fig.17
A delayed half-wave rectified sine wave of voltage shown in Fig.17. The delay angle is 450

170 . The value of Vav will be 54.4 V.

171 . The value of Vmax will be 47.7 V.

172 . Vav= 31.9V and Vmax=70.8V if delay angle is 900 .

173 . Vav= 9.32 V and Vmax=30.12 V if delay angle is 1350 .
Question 174 to 175 refer to Fig.18
Full wave rectified sine wave shown in Fig.18 has a delayed angle of 600.

174 . The average value of voltage will be 47.8 V.

175 . The rms value of voltage will be 63.3 V.

176 . A rectified sine wave is clipped at one half of its peak as shown un Fig.19. The rms value of the voltage will be 42.2 V.

177 . The effective value of voltage of the wave is clipped at 600, will be 66.8 V.