Semiconductors Questions and Answers

1 2 B NOR gate X AND gate ABC 000 100 Question Type Single Correct Type C D1 11 1 When the output of X is connected to the input Y the resulting combination is equivalent to A B3 0 1 1 0 Y B

Question Type Single Correct Type 1 N type germanium is negatively charged and P type germanium is positively charged 2 Both N type and P type germanium are neutral 3 N type germanium is positively charged and P type germanium is negatively charged Both N type and P type germanium are

The transfer ratio current gain of a transistor is 50 The input resistance of the transistor when used in the common emitter configuration is 1KQ The peak Value for an A C input voltage of 0 01 V peak is Question Type Single Correct Type 1 100 A 2 0 01 MA 3 0 25 mA

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To get an output below the input must be A a 0 b 0 c 1 B C 11 01 0 0 1 0 shown 2010 Y 84 85

The drift velocity of free electrons in a conductor of length 6 m is 0 25 ms under the application of potential difference of 100 V The mobility of free electrons is 2 x 103 m V S 1 2 5 x 10 2 m V s 1 1 5 x 10 m V S 1 1 5 x 10 m V S 1

A semiconductor X is made by doping a germanium crystal with arsenic Z 33 A second semiconductor Y is made by doping germanium with indium Z 49 The two are joined end to end and connected to a battery as shown Which of the following statements is correct X Y Question Type Single Correct Type 1 2 3 X is P type Y is N type and the junction is forward biased X is N type Y is P type and the junction is forward biased X is P type Y is N type and the junction is reverse biased

73 A p n photodiode is fabricated from a semiconductor with a band gap of 2 5 eV It can detect a signal of wavelength 2009 a 4000 nm c 4000 b 6000 nm d 6000 81 A B

55 In the following circuit the output Y for all possible inputs A and B is expressed by the truth table 2007 A B a ABY 011 011 101 110 c ABY 000 011 101 A B b ABY 001 010 100 110 d ABY 000 010 100 111 Y 70 a c 1 A p r band the ra is ne a c 71 The is e a c 72 The are

d 6000 A configuration A transistor is operated in common emitter at V 2 V such that a change in the base current from 100 A to 200 A produces a change in the collector current from 5 mA to 10 mA The current gain is 2009 a 100 c 50 b 150 2 75

Two cells of emfs approximately 5V and 10V are to be accurately compared using a potentiometer of length 400 cm NCERT Exemplar a The battery that runs the potentiometer should have voltage of 8V b The battery of potentiometer can have a voltage of 15 V and R adjusted so that the potential drop across the wire slightly exceeds 10 V c The first portion of 50 cm of wire itself should have potential drop of 10 V d Potentiometer is usually used for comparing resistan and not voltages

A compound generator is to supply a load of 250 lamps each rated at 100W 250 V the armature series and shunt windings have resistances of 0 06 2 0 04 2 and 50 respectively Determine the generated e m f when the machine is connected in i long shunt ii short shunt Take brush drop as 1 V per brush 6

A long cylinder having a diameter of 2 cm is maintained at 600 C and has an emissivity of 0 4 Surrounding the cylinder is another long thin walled concentric cylinder having a diameter of 6 cm and an emissivity of 0 2 on both the inside and outside surfaces The assembly is located in a large room having a temperature of 27 C Calculate the net radiant energy lost by the 2 cm diameter cylinder per meter of length Also calculate the temperature of the 6 cm diameter cylinder

A transistor configuration is operated in common emitter at V 2 V such that a change in the base current from 100 A to 300 A produces a change in the collector current from 10 mA to 20 mA The current gain is 1 25 3 75 AIPMT Prelims 2011 2 50 4 100

9 Pure Si at 500 K has equal number of electron n and hole n concentrations of 1 5 x 1016 m Doping by indium increases n to 4 5 102 m 3 The doped semiconductor is of AIPMT Mains 2011 1 n type with electron concentration n 2 5 1023 m 3 2 p type having electron concentrations n 5 x 10 m e 3 n type with electron concentration n 2 5 1022 m 3 e 4 p type with electron concentration n 2 5 1010 m 3 e

The input resistance of a silicon transistor is 100 0 Base current is changed by 40 A which results in a change in collector current by 2 mA This transistor is used as a common emitter amplifier with a load resistance of 4 k The voltage gain of the amplifier is AIPMT Mains 2012 1 2000 2 3000 3 4000 4 1000