PPSC Physics Full Book With Answers

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PPSC Physics Full Book

Sr. # Questions Answers Choice
1 at room temperature the p.d. between the two sides of depletion region for silicon is of the order of. 0.3 V 0.5 V 0.7 V 0.9 V
2 A charge less region which separates p-type and n-type semiconductors in a p-n junction is known as. Polar region Null region Depletion region Neutral region
3 The current passing across a p-n junction due to minority charge carriers is called Reverse current Forward current Leakage current Both a and b
4 A p-type material is formed then a semiconductor is doped with Trivalent impurity Tetravalent impurity All of above A material having excess of free electrons
5 In a n-type material there is an excess of. Free electrons Holes Quarks Measons
6 In half wave rectifier the rms value of A.C. component of the wave is. More than A.C. Value Less than D.C. value Same as that of D.C. Not detectable
7 Why is an oxide coated filament used in vacuum tube. It has a longer lime Irt can with stand high It emit electrons at low temperature It reduces the effect of space charge
8 Where is the velocity of electrons maximum in a diode. Near the cathode Near the anode In the space ini between the two elecrode. It is same throughout the tube
9 A vacuum diode conducts when plate Is negative w.r.t cathode Is positive w.r.t. cathode and cathode are at the same potential Resistance is less
10 Which of the following material could be used for a high vacuum, high voltage tube. Thoriated tungsten Tungsten Copper Cesium
11 The thermionic current increases when Area of filament is decreased Area of filament is increased Temperature is decreased Work function is increased
12 Efficiency of a half wave recitifier is. Almost negigible More than full wave rectifier Less than full wave rectifier Equal to full wave rectifier
13 When forwarded bias is applied to a junction diode it. Increases the potential barrier Decreases the potential barrier Reduces the majority carrier current to zero Reduces the minority carrier current to zero
14 Which of the following is not an application of diodes. A filters Bridge rectifier Half wave rectifier Full wave rectifier
15 Since a diode permits the flow of current only in one direction so it can be used as. An oscillator A rectifier A phot deflector A transistor
16 What for is semiconductor diode used. To convert D.C. to A.C. To convert A.C. to D.C. To increase voltage To decrease voltage
17 A forward based p-n semiconductor diode is called. Photodiode Photovoltaic cell Amplifier Ligh emitted diode
18 If we use two diodes and a centre tapped transformer we will get. A transistor An amplifier A half wave rectifier A full wave rectifier
19 Photo diodes are used as Optical fibre receivers Automatic switching Logic circuits All of the above
20 The eight most common element in the universe by mass is Ge C Si As
21 Pure silicon has valence electrons 1 2 3 4
22 The typical value of forbidden energy gap in germinium is. 0.7 eV 1.0 eV 1.4 eV 10 eV
23 Which one is not a semiconductor. Go As Ge Sc In
24 The most common trivalent impurities are Boron , indium Arsenic, indium Arsenic, Antimony Aluminium, Boron
25 With increase in temperature the electrical conductivity of intrinsic conductors. Increases Descreases Remain unaffected First increases then decreases
26 In a half wave rectifier the rms value of the A.C. component of the wave is. Less than D.C. value Great her than D.C. value Equal to D.C. value Zero
27 Select the one that is not a donar P AS Sb In
28 Which one of the following materials has negative temperature coefficient. Conductors Semiconductors Insulators Covalent bonds
29 A single silicon photovoltaic cell produces a current of the order of. A few miliamperes 10<sup>2</sup> A 10<sup>3</sup> A 10<sup>4</sup> A
30 A single silicon photovoltaic cell produces a voltage of the order of. 0.3 V 0.6 V 0.9 V 1.2 V
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