PPSC Physics Full Book With Answers

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PPSC Physics Full Book

Sr. # Questions Answers Choice
1 The advantage of LEDs over filament lamp is their Small size Reliability High operating speed All of the above
2 When light emitting diode is forward biased, it emits light of the colour Red Yellow Green All of these
3 In rectifiers silicon junction diodes are preferred to germanium type because. They are cheaper They are durable Their much lower reverse current makes them more efficient Of their geometry
4 If the output voltage is not smooth but pulsating then it can be made smooth by using a circuit known as. Filter Gate shunt Fuse
5 The circuit of full wave rectification consists of Only one diode Two diodes Three diodes Four diodes
6 The process due to which current flows only during alternate half cycle is known as. Filtration saturation Half wave rectification Full wave rectification
7 The process of converting A.C and D.C. is known as Amplification <sub>Filtration</sub> Rectification Saturation
8 If positive terminal of the battery is connected to n-type and negative terminal of the battery is connected to p-type then the diode is. Saturated A gate Forward biased Revere biased
9 A semiconductor diode conducts only when it is Not biased Zero biased Reverse biased Forward and biased
10
A diode cn be used as
 Amplifier Rectifier Oscillator Transistor
11 A junction between P-Type and n-type materials is called. Ampilifier Transistor Rectifier Diode
12 The process of mixing sound waves with carrier waves is known as. Rectification amplification Modulation Demodulation
13 In electronegative waves the electric and magnetic fields are. Parallel to each other Perpendicular to each other antiparallel to each other At an angle of 45 <sup>o</sup> to each other
14 The cosine of the phase angle between the current and voltage in an A.C. circuit is called the Lead factor Lag factor Dissipation factor Power factor
15 A choke coil is a coil with Low inductance and low resistance Low inductance and high resistance High inductance and low resistance Low inductance and negligible resistance
16 For an A.C. circuit the power factor is Always les than one Always greater than one Always equal to one Absent
17 The instantaneous voltage across a pure inductance. Leads the current by 90 <sup>o</sup> in phase Lags the current by 90 <sup>o</sup> in phase Is in phase with the current Leads the current by a phase angle which depends on the frequency
18 An A.C. dynamo operates on the principle of Mutual induction Self induction Electromagnetic induction Mechanical induction
19 In a purely resistive circuit carrying A.C. current the. Current and voltage are always in phase Current lags the voltage by 1/4 cycle Voltage lags the current by 1/4 cycle Current leads the voltage by 1/2 cycle
20 In modulation, low frequency signal is called Fluctuated signal Loaded signal Modulated signal Harmonic signal
21 As a result of modulation, the resultant wave is called. Carrier wave Modulated carrier wave Matter wave Energetic carrier wave
22 High frequency radio wave is called Fluctuate wave Carrier wave Matre wave Energetic wave
23 The process of combining low frequency signals with high frequency radio waves is called. Modulation Resonance Fluctuation Amplitude
24 The electromagnetic waves propagated outing space from antenna of a transmitter are known as. Infrared waves Light waves Radio waves X-rays
25 In an A.C. circuit the current. Is in phase with voltage Leads the voltage Lags the voltage Any of these depending upon the circumstances
26 Alternating current generator consists of a coil and a pair of. Split rings Slip rings Metal rings Copper rings
27 The effective resistance in an A.C. circuit is An inductance An impedance A mutual inductance Always zero
28 What for is a modulator circuit used. To eliminate carrier waves To superpose the radio frequency signal on the carrier waves To transmit the signal To create sound waves
29 The picture to be transmitted must be scanned because in T.V transmission light wave are first changing into. sound wave Electric fluctuations Magnetic fluctuations Signals
30 When the frequency of A.C in L - C- R circuit is incrased the impedance of L-C-R circuit. Increase Decrease Remain unchanged First decrease and then increases
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