Physics Chapter 7 – Electronics (Class 12) for FSC, Entry Tests & NTS Preparation
Chapter 7, Electronics, is an important topic for Class 12 students preparing for FSC board exams and engineering entry tests like ECAT, NUST, and FAST, as well as NTS exams. This chapter explains the fundamental principles of electronic devices and circuits, focusing on components that control the flow of electrons. Understanding electronics is essential for studying modern electrical devices, communication systems, and digital technology.
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The electron volt is the unit of __________.
PMC Practice 3
Physics
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When transistor Is forward biased then resistance will be: b a) Nano ohms ) Kilo ohms c) Mega ohms
A half-wave rectifier uses:
PMC Practice 13
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If peak voltage across a full wave rectifier is 20V then Vrms is:
PMC Practice 10
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The ripple factor of half-wave rectifier is?
PMC Practice 14
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A semiconductor photodiode is a:
NTS 2011
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Which option in the following best explains Base of a transistor?
NUMS 2017
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Consider a peak rectifier fed by a 60-Hz sinusoid having a peak value Vp = 100 V. Let the load resistance R = 10 kΩ. Calculate the fraction of the cycle during which the diode is conducting:
PMC Practice 13
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Majority charge carriers in P-type semiconductor are
PMC Sample 2
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A full wave rectifier uses load resistor of 1500 Ω. Assume the diodes have Rf= 10 Ω, Rr= ∞. The voltage applied to diode is 30V with a frequency of S0Hz. Calculate the AC power input.
PMC Practice 14
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If the temperature of diode increases the leakage current will
PMC Sample 2
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To get a peak load voltage of 40V out of a bridge rectifier, what should be the approximate rms value of secondary voltage?
PMC Practice 5
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A logic gate has four inputs. Its possible input combinations will be:
NUMS 2015
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The number of diodes in centre-tapped full-wave rectifier is:
PMC 2021 Tested
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Transistors can be used as:
PMC Practice 10
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When an Operational amplifier is used as Inverting amplifier, then angle between its output and input signal is:
NUMS 2019 Cancelled
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The process of converting alternating current to direct current is called?
PMC Practice 14
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If the input frequency of a full-wave rectifier is 50 Hz, its ripple frequency is:
PMC 2021 Tested
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If x and y are the input of the GATE, and z is the output, the following table represents:
Which of the following is a type of rectifier?
PMC Practice 15
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Operational amplifier with an LDR is used as a:
NUMS 2019 Reconduct
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Consider a peak rectifier fed by a 60-Hz sinusoid having a peak value Vp = 100V. Let the load resistance R = 10kΩ . Calculate the fraction of the cycle during which the diode is conducting:
PMC Practice 5
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The open-circuit test in a transformer is used to measure?
PMC Practice 3
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The width of depletion region Increases due to:
In photodiodes, the bias voltage is applied in ______ bias form.
NTS 2016 DUHS & JSMU
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In the breakdown region zener behaves like a
PMC Sample 2
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At least how many diodes are required to covert A.0 fully into D.C?
In a centre tap full wave rectifier if Vm is the peak voltage across the secondary of transformer, the maximum voltage across reverse bias is
PMC Practice 11
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When semi-conductors dopped In
then they are p-type
In half-wave rectification, the output DC voltage is obtained across the load for ______.
PMC Practice 9
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A transistor cannot be used as
If both inputs “A” and “B” are ON and the output is also ON. This type of gate is known as:
NUMS 2017
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A diode works in ___ bias for rectification.
PMC Practice 11
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In full wave rectifier with input frequency 50 Hz the ripple in the output is mainly of frequency
PMC Practice 6
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______ is equivalent to AND Gate followed by a NOT Gate.
NUMS 2017
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The half wave rectifier has how many diodes?
PMC 2021 Tested
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The basic purpose of filter is to?
PMC Practice 1
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Input resistance of an Operational Amplifier is:
NUMS 2019 Reconduct
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Non-inverting amplifier circuits have?
PMC Practice 2
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Half wave voltage multiplier can provide any degree of voltage multiplication by cascading diodes and capacitors.
PMC Practice 12
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Which two or more of the following actions would increase the energy stored in a parallel plate capacitor when a constant potential difference is applied across the plates:
PMC Practice 5
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A negligible small current between input terminals of the operational amplifier is because of:
UHS 2019
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Which of the following is not a type of rectifier?
PMC Practice 12
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In half wave rectification, the output DC voltage is obtained across the load for?
PMC Practice 10
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In a npn transistor, the current IEthat flows in the emitter circuit is:
NTS 2016 DUHS & JSMU
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A type of metals containing alloys, ceramics etc., when heated their temperature reaches to a state called Transition temperature state and their resistance reaches to zero. These types of metals are called:
Gamma rays are attracted towards
PMC Practice 11
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In full wave rectifier with input frequency 50 Hz, the ripple in the output is mainly of frequency?
PMC Practice 10
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The principle behind the working of cathode ray oscilloscope is:
PMC Sample 1
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Magnetism and Electromagnetic Induction
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A signal of -80 mV is applied to the inverting terminal of the amplifier while the non inverting terminal is grounded. The gain of the amplifier is 25 using Rin(R1) equal to 3 ohms and Rf(R2) equal to 75 Ohms. What would be the value of the output signal?
UHS 2018
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Which of the following rectifier uses a wheatstone bridge to rectify signals?
PMC Practice 13
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AC is converted to D.C by:
A capacitor and an inductor are connected to A.C. supply. If we double the frequency of A.C. supply then the effect on reactance of capacitor XC and reactance of inductor XL will be:
NUMS 2019 Cancelled
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A cable 4 km long and of total resistance 1 Ohm carries electric current from a generator producing 100kW at 10,000 Volts. The current in amperes in the cable is:
PMC Practice 5
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Maximum efficiency of half wave rectifier is:
PMC Practice 11
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Full wave rectifier uses:
PMC Practice 5
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A full wave rectifier is operating from 50 Hz mains, fundamental frequency of ripple will be
PMC Sample 2
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When reverse bias of a p-n junction diode is increased, a stage comes when electric field set up is sufficient to rupture covalent bonds and release a large number of holes and electrons. This breakdown phenomenon is known as:
NUMS 2018
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Key Concepts about Electronics
The chapter explains the behavior and characteristics of electronic components such as diodes, transistors, and semiconductors. It covers rectifiers, amplifiers, and logic gates, as well as their applications in practical circuits. The chapter also discusses analog and digital signals, basic circuit design, and the use of electronics in communication and control systems. Each concept is illustrated with diagrams, examples, and step-by-step explanations. These concepts are highly important for FSC board exams and engineering entry tests like ECAT, NUST, and FAST.
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Mastery of electronics helps students understand electronic devices, solve numerical and circuit problems, and apply concepts to real-world systems. PLS Academy provides practice questions, solved past papers, and chapter-wise MCQs to help students revise these topics effectively. Regular study of this chapter improves problem-solving skills, conceptual clarity, and exam performance, ensuring students are well-prepared for FSC board exams, competitive entry tests, and NTS exams.
JazakAllah.
