76. The intrinsic carrier concentration of silicon sample at 300 K is 1.5 x 1016/m3. If after doping, the number of majority carriers is 5 x 1020/m3. The minority carrier density is
77. A diode is operating in forward region and the forward voltage and current are v = 3 + 0.3 sin ωt (volts) and i = 5 + 0.2 sin ωt (mA). The average power dissipated is
78. Two identical silicon diodes D1 and D2 are connected back to back shown in figure. The reverse saturation current Is of each diode is 10-8 amps and the breakdown voltage VBr is 50 v. Evaluate the voltages VD1 and VD2 dropped across the diodes D1 and D2 assuming KT/q to be 25 m V.
79. For BJT transistor. The maximum power dissipation is specified as 350 mW if ambient temperature is 25°C. If ambient temperature is 60°C the maximum power dissipation should be limited to about
80. The concentration of minority carriers in a semiconductor depends mainly on
81. Which of the following has highest conductivity?
82. In a bipolar junction transistor the base region is made very thin so that
83. Compared to bipolar junction transistor, a JFET has
84. The drain characteristics of JFET in operating region, are
85. As temperature increases
86. When a reverse bias is applied to a p-n junction, the width of depletion layer.
87. The Hall constant in Si bar is given by 5 x 103 cm3/ coulomb, the hole concentration in the bar is given by
88. Which of the following devices has a silicon dioxide layer?
89. Which statement is false as regards holes
90. Photo electric emission can occur only if
91. The reverse saturation current of a diode does not depend on temperature.
92. In a piezoelectric crystal, application of a mechanical stress would produce
93. The value of a in a transistor
94. Which of these has 3 layers?
95. As per Einstein's equation, the velocity of emitted electron in photoelectric emission is given by the equation
96. For an P-channel enhancement type MOSFET determine the drain current if K = 0.278 x 10-3A/V2, VGS = -4V, VT = -2V, Voltage equivalent at 27°C = 26 mV.
97. The skin depth of copper is found to be 66 mm at 1 MHz at a certain temperature. At the same temperature and at 2 MHz, the skin depth would be approximately
98. When p-n junction is reverse biased the holes in p material move towards the junction and electrons in n material move away from the junction.
99. A semiconductor diode is biased in forward direction and carrying current I. The current due to holes in p material is
100. Between which regions does BJT act like switch?