CBSE Class 12 Physics Revision Notes Chapter 14

Class 12 Physics Chapter 14 Notes- Semiconductor Electronics: Materials, Devices and Simple Circuits

Physics requires students to think analytically as well as critically. This can be achieved only if they have  the right study material to follow. As a result, experts suggest students look for authentic study material in the market. If they do so,  they will find it easier to deal with Physics and score well in their examinations.

Demand for semiconductors in the market is increasing rapidly due to their applications in various domains. Electronic devices such as Mobile phones, Laptops, Computers etc., cannot function properly without semiconductors.. Moreover, it is used in various instruments and industries such as industrial electronics, defence & space industry, transportation, healthcare and much more to get better and make faster advances, a multitude of electronic products are required. . Hence, the usage of semiconductors is increasing rapidly. .

In such cases, the students must have complete information about semiconductors. As a result, the chapter Semiconductor Electronics: Materials, Devices and Simple Circuits has been included in the Class 12 Physics syllabus. The chapter covers essential topics like Classification of Metals, Conductors and Semiconductors on the basis of energy bands which is explained in different cases and situations on the basis of the gap between the bands. 

Other significant topics, such as intrinsic semiconductors and extrinsic semiconductors, are subdivided into p-type and n-type. It also includes p-n junction formation, semiconductor diode, p-n junction diode under forwarding bias, p-n junction diode under reverse condition, applications of junction diode as a rectifier, special purpose p-n junction diode, digital electronics and logic gates.

It is quite necessary that students are completely aware of this chapter. Extramarks provides Class 12 Physics Chapter 14 notes with complete explanations. It is designed based on the latest CBSE curriculum. It has all the key points, vital concepts, theories and experiments which help students to learn with better understanding. It also includes sets of important questions for students to quickly test themselves after completing a chapter. As a result, students gain confidence after referring to it.  By practising solved exercises and practice questions these notes help to clear their doubts and strengthen their base. 

They can get Class 12 Physics Chapter 14 notes from the Extramarks website. Along with this, it provides notes for other subjects like Chemistry, Mathematics, Biology and English. They can refer to all the notes by registering on the official website.   Extramarks is a perfect platform for students to excel and score well in their examinations.  These notes prepared by experienced faculty are reliable and accurate. No wonder students have complete trust and faith in Extramarks.  

Key Topics Covered in Class 12 Physics Chapter 14 notes.

Semiconductors have a wide range of applications due to their compactness, reliability, performance, power efficiency and durability. The significant advantage is that it is reasonably priced and competitive edge. . The scope of semiconductors is immense in almost all industries.  They’re responsible for powering all of our devices, from smartphones and laptops to TVs and cars.  The market has a great demand for it

The chapter Semiconductor Electronics: Materials, Devices and Simple Circuits covers essential topics like Classification of Metals, Conductors as well as Semiconductors on the basis of the energy bands, which is explained in different cases and situations on the basis of the gap between the bands.

You can find complete details about the chapter in the Class 12 Physics Chapter 14 notes available on the Extramarks website and leverage your performance by referring to it.   because these notes strictly follow the NCERT books which adhere to the CBSE curriculum. Students can completely rely on these notes.  Be an early bird and make a difference.

After finishing the chapter, you will be able to distinguish between metals, conductors and semiconductors on the basis of conductivity and the energy bands, intrinsic and extrinsic semiconductors, n-type and p-type semiconductors, and p-n junction diode under forwarding bias and under backward bias. You will get a clear-cut understanding of Zener diodes and logic gates.

INTRODUCTION

Semiconductors are the study of the working of various applications of electronics. It helps make the device work faster with better efficiency at a low cost. Thus, it is an integral part of day-to-day life.

The chapter Semiconductor Electronics: Materials, Devices and Simple Circuits cover essential topics like Classification of Metals, Conductors as well as Semiconductors on the basis of energy bands which is explained in different cases and situations on the basis of the gap between the bands.

Students may refer to  Class 12 Physics Chapter 14 notes on the Extramarks website for a complete explanation of the chapter with examples.

CLASSIFICATION OF METALS, CONDUCTORS AND SEMICONDUCTORS

Metal is a substance having high electrical as well as thermal conductivity. It has malleability, ductility and strong resistivity.

A substance which allows electricity to pass through it is known as a conductor.

The substance having properties between conductor and insulator is called a semiconductor.

In this chapter, we will gain complete knowledge about semiconductors and their wide range of applications in devices.

 Students can find more information about it in the Class 12 Physics Chapter 14 notes on the Extramarks website.

• On the basis of conductivity

According to the relative values of the electrical conductivity (σ ) as well as the resistivity (ρ = 1/σ ), the solids are primarily categorised as 

(i) Metals: The solids that possess very small resistivity (or large conductivity) and its range is given below,

ρ ~ 10-2 – 10-8 Ω m 

And 

σ ~ 102 – 108 S m-1 

(ii) Semiconductors: The solids that have resistivity and conductivity intermediate to the metals and the insulators, and its range is given below,

ρ ~ 10-5 – 106 Ω m 

And

σ ~ 105 – 10-6 S m-1  

(iii) Insulators: The solids that have high resistivity (or low conductivity) and its range is given below, 

ρ ~ 1011  – 1019  Ω m 

And

σ ~ 10-11  – 10-19  S m-1  

ρ and σ values show the magnitude of the solids, but the ranges can also go beyond. These values are not only the criterion for differentiating between metals, conductors and semiconductors. There are many other factors which we will learn more in-depth as we proceed further. .

There are different types of semiconductors. The following are the types we will be mainly focussing on  in this chapter:

(i) Elemental semiconductors include: Si and Ge 

(ii) Compound semiconductors have examples as-

• For Inorganic: CdS, GaAs, CdSe, InP, etc. 
•  For Organic: anthracene, doped phthalocyanines, etc. 
• For Organic polymers: polypyrrole, polyaniline, polythiophene, etc. 

Most semiconductor devices function on the basis of elemental semiconductors Si or Ge and compound inorganic semiconductors. 

With the advancement of sciences, organic semiconductors and semiconducting polymers were used in many semiconductor devices, which enhanced the involvement of polymer electronics and molecular electronics. But in this chapter, we will broadly discuss elemental semiconductors Si and Ge. The concepts applied in the working of elemental semiconductors will also be used in most compound semiconductors too.

You will get an in-depth understanding of the topic, once you refer to the CBSE Class 12 Physics Chapter 14 notes available on the Extramarks website.

• On the basis of energy bands

The energy of the electrons of an isolated atom is analysed by the orbit in which it moves. This is what we have learnt in the Bohr atomic model. In the case of solid formations, the condition is not the same. The atoms come together and close to each other when forming a solid. The resulting neighbouring atoms having outer orbits of electrons may come very close or could even overlap. This distinguishes between the movement of the nature of the electron from the nature of the isolated atom.

The position of electrons is significant in each crystal, and the exact pattern of charges is not seen in any two electrons. As a result, electrons show differing energy levels. These different energy levels with repeating energy variations form the energy bands. The energy band, which has the energy levels of the valence electrons, is known as the valence band. The energy band which is on top of the valence band is known as the conduction band.

All the valence electrons lie in the valence band if there is none of the external energy. When the lowest level in the conduction band occurs to be lower than the highest level of the valence band, so the electrons from the valence band subsequently move into the conduction band. Usually, it is empty. However, when it coincides with the valence band, electrons can go quickly into it. This is the condition for the metallic conductors. 

When we notice a huge gap between the conduction band and the valence band, electrons are found in the valence band, and the conduction band remains empty. This is the case for the insulator. 

In some conditions, the electrons may gain some extra energy to cross the gap between the conduction band and the valence band. 

In such a case, the electrons may move into the conduction band. Simultaneously, they will give rise to empty energy in the valence band. Thus, the conduction is due to electrons in the conduction band as well as vacancies in the valence band.

You can find complete details in the notes of Class 12 Physics Chapter 14 available on the Extramarks website.

• Band Theory of Solids

An electron of each atom has different energies in different orbits. We know that the atoms are closer to each other, and hence the electrons interact. The outermost obits electrons are overlapping. Thus, to understand the energy pattern in Si and Ge, we only need to study the energy of the outermost orbital electrons.

When the electrons come together to form a solid, the outermost electron of the orbit may increase or decrease due to interaction between the electrons of different atoms. The energies in the different orbitals spread out and form the energy band, and the gap between them is known as the energy gap.

At a much smaller distance, there comes a region in which the bands merge with each other. If the distance between the atoms further becomes less, the energy bands again split apart and are separated by an energy gap Eg. 

Therefore, this band also known as the valence band is completely filled while the upper band is entirely empty. Hence, the upper band is known as the conduction band.

The lowest energy level for the conduction band is denoted as Ec, and the highest energy level of the valence band is represented as Ev. Above Ec as well as below Ev, there are a massive number of closely spaced energy levels.

The gap between the valence band’s top and the conduction band’s bottom is known as the energy band gap (Energy gap Eg ). Depending upon the material, this may be large, small, or zero.       

  Case I:

This case is seen for the materials having low resistance and high conductivity. A metal is noticed when the conduction band is not completely filled and the valence band is partially empty or overlaps. When there is a condition of overlapping, the electrons can quickly move from the valence band to the conduction band. This gives rise to electrical conductivity. If the valence band is partially empty, then electrons from the lower level move to the higher level. This makes conduction possible.

Case II:

In this case, a big gap between the bands is noticed, which is at (Eg > 3 eV). One cannot find electrons in the conducting band, so there is no electrical conductivity. The gap in the energy levels is so high that the electrons cannot be taken to higher levels or excited from the valence band to the conduction band by thermal conductivity. This is observed for insulators.

Case III:

This is contradictory to case II. The gap between the band energy levels is as follows  (Eg < 3 eV). Due to a lesser band gap, electrons get some energy to cross the valence band and have been moved to the conduction band at room temperature. Thus, a small number of electrons, in this case, can move to the conduction band. This is for the semiconductors, which are intermediate to conductors and insulators.

Here we study a brief explanation of the band theory of solids. Students can clear the concepts by practising a lot of questions which are available on  Extramarks website. Students can refer to the Class 12 Physics Chapter 14 notes to help them understand how to solve the different kinds of problems in a step-by-step manner. If they ever get stuck on a question, they can always refer to the notes prepared by subject matter experts which also cover exercises and additional exercises to master the topic. 

All the cases, topics and subtopics in the Chapter 14 Physics Class 12 notes are available on the Extramarks website.

Intrinsic Semiconductor

In the case of Ge and Si, each atom has four valence electrons. They have the tendency to share each of their valence electrons with the neighbouring atoms. These valence electrons form a covalent bond. When the temperature increases, the amount of thermal energy available to these electrons is more, and some of the electrons may break–away (becoming free electrons contributing to conduction). 

The thermal energy then ionises only a few atoms in the crystalline lattice, creating an empty space in the bond. The neighbourhood, from where the free electron (with charge –q) has come out, leaves an open space with an effective charge (+q ). These vacancies with the effective positive electric charge are known as the hole. The hole acts as a relative free particle with some positive charge. 

For the intrinsic semiconductors, the various number of free electrons ne equals the various number of holes, nh. which is ne = nh = ni 

Here, ni is called intrinsic carrier concentration. 

Semiconductors possess a significant property in which the holes also move along with the electrons. Under the action of an electric field, the holes travel towards negative potential giving the hole current, I h. The total current, I am thus the addition of the electron current Ie and the hole current I h: 

I = Ie + Ih. 

It may be considered that apart from the process of generation of conduction electrons as well as holes, a simultaneous process of recombination occurs in which the electrons recombine with the holes. At equilibrium, the generation rate equals the rate of recombination of charge carriers. The recombination occurs due to the electron hitting a hole. 

An intrinsic semiconductor will act as an insulator at T = 0 K. It is the thermal energy at higher temperatures (T > 0K) which accelerates some electrons from the valence band to the conduction band. These thermally accelerated electrons partially occupy the conduction band at T > 0 K.

To get more details about the Intrinsic Semiconductor, the student can refer to our study material and clarify their doubts and strengthen their concepts by various questions given in end text exercises. Our study material is available on  Extramarks’ website students can refer to the Class 12  Physics  Chapter 14 notes. 

The Class 12 Physics Chapter 14 notes on the Extramarks website cover all about intrinsic semiconductors as well as other topics.

Extrinsic Semiconductor

For a small amount, for instance, a few parts per million (ppm), of a little impurity is combined with the pure semiconductor, and the conductivity of the semiconductor is increased to a great extent. Such materials are called extrinsic semiconductors or impure semiconductors. The deliberate addition of the desirable impurity is called doping, and the impurity atoms are known as dopants. Such a material is also called a doped semiconductor. An essential condition is that the dopant and the semiconductor atom’s sizes should be nearly equal, for this condition to exist. 

There are two kinds of dopants used in case of the doping of the tetravalent Si or Ge: 

(i) Pentavalent (valency 5); Arsenic (As), Antimony (Sb), Phosphorous (P), etc.

(ii) Trivalent (valency 3) such as Indium (In), Boron (B), Aluminium (Al), etc. 

• (i) n-type semiconductor

When an atom has a +5 valence element, it takes the position of the atom in the crystal lattice for Si. Four of its electrons are bound with four silicon neighbours. At the same time, the fifth remains are relatively weakly bound to the parent atom. This is because the four electrons involved in bonding are seen as a part of the effective core for the atom by the fifth electron. 

Thus, the ionisation energy required to set the electron free is minimal, and even at room temperature, it will be free to revolve in the semiconductor lattice. For instance, the energy required is ~ 0.01 eV associated with germanium, and 0.05 eV associated with silicon, to separate the electron from the atom. This is contrary to the energy required to transition the forbidden band (about 0.72 eV for germanium as well as about 1.1 eV for silicon) at room temperature. 

In a doped semiconductor, the sum total of the number of conduction electrons ne is because of the electrons contributed by donors for ones generated intrinsically, which is the total of holes nh is because of the holes from the intrinsic source. H Hence the rate of recombination of holes would enhance due to the growth in the number of electrons. Thus, the number of holes would get reduced further.

Thus, with the proper level of doping, the number of conduction electrons can be made much larger than the number of holes. Hence in an extrinsic semiconductor doped with a pentavalent impurity, electrons become the majority carriers and hole the minority carriers. These semiconductors are thus known as n-type semiconductors. In n-type semiconductors, we have 

ne >> nh

You can find complete details of n-type semiconductors in the Class 12 Physics Chapter 14 notes on the Extramarks website.

 (ii) p-type semiconductor

When a small amount of trivalent impurity has been combined with a pure crystal with crystal growth, the produced crystal can be called a P-type extrinsic semiconductor.

The following key points should be recalled in the case of the P-type semiconductor:

(i) The majority charge carriers are the holes, whereas minority charge carriers are the electrons in the P-type semiconductor materials.

(ii) The P-type semiconductor will remain electrically neutral as the total number of movable holes under all conditions remains the same as the number of the acceptors.

To clear the concepts of p-types semiconductors, students can visit our website and refer to the Class 12 Physics Chapter 14 notes. 

p-n Junction

A p-n junction work has been applied in semiconductor devices like diodes, transistors, etc. We need to understand the working of the junction behaviour to analyse other semiconductor devices. Let us know how a junction formation happens and the junction’s behaviour under the influence of externally applied voltage, also known as bias.

• p-n junction formation

Consider p-type silicon (p-Si) semiconductor wafer. Then, we combine a pentavalent impurity with it. Due to this, a small part of the p-Si wafer is changed into an n-Si. Then, the wafer had a p-region and an n-region with a metallurgical junction between them. Two vital processes take place during the formation of a p-n Junction:

that is

Diffusion and Drift

In the n-type semiconductor, the concentration of the electrons is far more than that of the holes. Conversely, in a p-type semiconductor, the holes’ concentration is relatively higher than that of electrons.

When a p-n junction forms, the holes diffuse from the p-side to the n-side (p→n), whereas the electrons diffuse from the n-side to the p-side (n→p). This happens due to the concentration difference across the p and n sides. A diffusion current across the junction is created in it.

Students can find more details in the Class 12 Physics Chapter 14 notes available on the Extramarks website.  

Semiconductor Diode

A semiconductor diode behaves just as a p-n junction with the metallic connection provided at the ends for regulating an external voltage. It is a two-terminal device. A p-n junction diode is represented symbolically.

• p-n junction diode under forwarding bias

The p-n junction diode is defined as forward biased if the external DC source has been connected to the diode with the p– junction connected to the positive pole and the n– junction connected to the negative pole.

• p-n junction diode under reverse bias

The p-n junction diode is reverse biased if an external DC battery has been connected to a junction diode with a p-junction connected to the negative pole and an n-junction attached to the positive pole.

For more information, refer to the Class 12 Physics Chapter 14 notes on the Extramarks website.

Application of Junction Diode as a Rectifier

When an alternating voltage is used through a diode, the current flows only at the part of the cycle when the diode is forward-biased. This phenomenon helps to rectify alternating voltages, and the circuit used for this is called a rectifier. 

If an alternating voltage is used through a diode in series with a load, a pulsating voltage will be seen across the load only during the half cycles of the AC input for which the diode is forward biased. This rectifier circuit is called a half-wave rectifier. 

In the positive half-cycle of the AC, there is a current passing through the load resistor RL, and thus we get an output voltage when there is no current in the negative half cycle. In the following positive half-cycle, again, we find the output voltage. Despite varying output voltage, it is restricted to only one direction and is said to be rectified. The rectified output of such a circuit is only for half of the input AC wave; it is called a half-wave rectifier. 

The circuit using two diodes gives output rectified voltage corresponding to both the positive as well as negative half of the AC cycle. Hence, it is called a full-wave rectifier. 

The rectified voltage has the form of pulses in the shape of half sinusoids. Even if it flows in one direction, it does not show a fixed value. 

if the voltage across the capacitor is rising, it gets charged. If there is not any external load, it remains charged to the peak voltage of the rectified output. If there is a load, it gets discharged through the load, as well as the voltage across it begins to fall. In the next half-cycle of the rectified output, it again gets charged to the peak value. The rate of fall for the voltage across the capacitor depends inversely upon the product of capacitance C as well as the effective resistance RL used in the circuit and is called the time constant. 

To clarify their concepts, students must refer to the Class 12 Physics Chapter 14 notes on the Extramarks website.

Special Purpose p-n Junction Diodes

In the section, we will discuss a few devices which are basically junction diodes but are made for different applications.

Zener diode

Zener developed a p-n junction diode in the reverse bias. It functions in the breakdown region. It is used for voltage regulating. The symbol for a Zener diode is:

It is made through heavily doping both p and n sides of the junction. This leads to the formation of a very thin depletion region as well as an extremely high electric field across the junction, even for the small reverse bias voltage (~5 V). 

Now, we get that the reverse current is created due to the movement for the minority charge carriers. Electrons from the p-side move to the n-side, and then the holes from the n-side move to the p-side. As we increase the reverse bias voltage, then the electric field at the junction becomes stronger.

At V=Vz, the electric field is much stronger enough to pull the valence electrons from the host atoms on the p-side, which gets excited to the n-side. It explains the sudden increase in current. The process of emission of electrons from the host atoms due to the high electric field is known as Internal Field.

Students can visit our Extramarks website and refer to the Class 12 Physics Chapter 14 notes to find more information on this topic.

Zener diode as a voltage regulator

By now, we get that even if we use a rectifier to convert AC input voltage, the output fluctuates too. A Zener diode is required to get constant DC voltage from a DC unregulated output of a rectifier.

• The decrease in the input voltage decreases the current through Rs and the diode.
• The voltage drop across Rs decreases
• The voltage across the Zener diode does not change

. Therefore, an increase/decrease of the voltage drop across the Rs does not change the voltage across the Zener diode. Hence, it performs as a voltage regulator.

Get complete information about this topic in our Class 12 Physics Chapter 14 notes on the Extramarks website.

Optoelectronic junction devices

Till now, you have already learnt about how semiconductor diodes behave under electrical inputs. Now, let’s get to know about how they react to photo-excitation. These are the optoelectronic devices or devices in which the photons generate carriers. Let’s look at three such devices:

1. Photodiodes for detecting optical signals
2. Light Emitting Diodes (LEDs)
3. Solar cells

To get authentic and reliable study material, students can visit our Extramarks website and refer to Class 12 Physics Chapter 14 notes. 

(i) Photodiode

This is a special case of a p-n junction diode operated in reverse bias. It is designed with a transparent medium to allow light to fall on it. If the photons with the energy (hv) are more than the energy gap of the semiconductor, it falls on it, and the electron-hole pairs have been generated. The diode is designed in the manner that these electron-hole pairs are generated in or near the depletion region.

Thus, the electric field at the junction ensures that the electrons and holes are separated before they recombine. Hence, the direction of the electric current is to ensure that the electrons reach the n-side and holes get the p-side. This gives rise to an EMF.

Current flows on connecting with an external load. Also, this photocurrent’s magnitude depends on the intensity of the incident light. The direct correlation between the two is easy to observe with the application of a reverse bias. Hence, a photodiode can help to detect optical signals.

To learn more about photodiodes, students can visit our website and refer to Class 12 Physics Chapter 14 notes.

(ii) Light-emitting diode

A LED is a highly doped p-n junction which emits spontaneous radiation under forwarding bias. It is covered in a capsule with a  transparent cover allowing the emitted light to come out. Being forward biased, electrons move from the n to the p-side, and holes move from the p to the n-side.

So, the concentration of the minority carriers is higher near the junction as compared to the equilibrium concentration. Therefore, at the junction, on either side, excess minority carriers recombine with the majority carriers. This releases energy in the form of photons. The photons emitted have energies equivalent to or less than the band gap.

Another thing to remember here is that the intensity of the emitted light is small when the forward current is small. The intensity of the emitted light is enhanced as this current increases and reaches a maximum value. Post this, an increase in forwarding current leads to a decrease in the light intensity.

Commercially available LEDs can emit red, yellow, orange, green and blue light. LEDs are used extensively in remote controls, optical communication, etc. Here are some advantages of LEDs over incandescent low-power lamps:

• Low operational voltage as well as less power.
• Fast action as well as no warm-up time required.
• The bandwidth of emitted light is from 100 Å to 500 Å. Or in the other words, it is nearly (but not exactly) monochromatic.
• Long life and ruggedness.
• Fast on-off switching capability.

To know more about light-emitting diodes in-depth, students can visit our website and refer to Class 12 Physics Chapter 14 notes.

(iii) Solar cell

A solar cell is the p-n junction which generates EMF when solar radiation falls on it. The working principle is similar to the photodiode except that no external bias is applied, and the junction area is much larger to enable solar radiation incidence. This is how a simple p-n junction solar cell looks:

When sun rays fall on a solar cell, the EMF is generated due to these three processes:

• Generation of the electron-hole pairs due to light (with hν > Eg) close to the junction
• Separation of the electrons and holes due to the electric field of the depletion region. Electrons are swept to the n-side and holes to the p-side.
• Collection – the electrons reaching the n-side are collected by the front contact, and holes reaching the p-side are managed by the back contact. Thus the p-side becomes positive, and the n-side becomes negative, giving rise to photo-voltage.

A detailed analysis is provided in the Class 12 Physics Chapter 14 notes available on the Extramarks website.

Digital Electronics and Logic Gates

In electronics circuits like amplifiers, and oscillators, introduced to you in the earlier sections, the signal (current or voltage) have been in the form of the continuous, time-varying voltage or the current. Such signals are called continuous or Analog signals. 

Only two values (denoted by 0 or 1) of the input and output voltage are permissible in digital circuits.

This section is intended to provide us with the first step in our understanding of digital electronics. We should restrict our study to some basic building blocks of digital electronics (called Logic Gates), these process the digital signals in a very specific manner. Logic gates are used in calculators, digital watches, computers, robots, industrial control systems, and telecommunications. 

We provide the study material based on NCERT books which strictly follow CBSE curriculum. Students can visit our  Extramarks website and refer to Class 12 Physics Chapter 14 notes. 

• Logic gates

For digital devices to function the way they do, logic needs to be established between the input as well as output voltages. These are achieved by using a gate or a digital circuit that should follow the logical relationship. Since they control the flow of information based on a certain logic, they are called logic gates.

Each logic gate is indicated by a symbol and has a truth table which displays all possible input-output combinations. In short, the truth tables help understand the behaviour of the logic gates. These gates are made using semiconductor devices. The five most majorly used logic gates are:

• NOT
• AND
• OR
• NAND
• NOR

Let’s study each one of them in detail.

1. NOT gate

A simple gate with one input and one output, a NOT gate simply inverts the input signal. So, the output is ‘0’ when the input is ‘1’ and vice-versa. Due to this property, a NOT gate is also known as an inverter. Here is the commonly used symbol for a NOT gate:  

2. OR gate

An OR gate has two or more inputs and one output. The logic of this gate is that the output would be 1 when at least one of the inputs is 1. Simply put, the output is high when any of the inputs is high. The commonly used symbol for an OR gate is as follows:

And the truth table for an OR gate is as follows:

3. AND gate

An AND gate also has two or more inputs and a single output. In this gate, the output is 1 when all the inputs are 1. In other words, the output is high when all the inputs are high. The most commonly used symbol for an AND gate is as follows: 

The truth table for AND gate is given by:

4. NAND gate

A NAND gate is simply an AND gate followed by a NOT gate. The output is 1 only when all inputs are NOT 1. Or the output is high when all the inputs are NOT high, and at least one of them is low. These are also called Universal gates since the earlier three gates can be realised by using the NAND gate. The commonly used symbol for a NAND gate is as follows:

And the truth table for a NAND gate is as follows:

As seen above, it is the opposite of an AND gate – (NOT+AND = NAND).

5. NOR gate

A NOR gate is simply an OR gate followed by a NOT gate. The output is 1 only when all inputs are 0. Or the output is high when all the inputs are low. These are also called Universal gates since the earlier three gates can be realised by using the NOR gate. The commonly used symbol for a NOR gate is as follows: 

And the truth table for a NOR gate is as follows:

As seen above, it is the opposite of an OR gate – (NOT+OR = NOR). 

Students can visit our Extramarks website and refer to the Class 12 Physics Chapter 14 notes to learn more about the logic gates.

Class 12 Physics Chapter 14 notes Exercise & Solutions.

Understanding some of the vital concepts of Physics requires a lot of practice-oriented approaches while studying. This could be achieved by implementing regular practice sessions in study schedules. All the exercises given in the NCERT textbook are crucial as they cover every concept of the chapter. . As a result, Extramarks provide a detailed solution to every question in the chapter’s exercises. In turn, helping students to be better performers in Physics.

All the solutions are designed as per the latest curriculum of CBSE, ensuring students that they study everything that is included in the chapter. Students can also find additional questions related to the given concepts in the Class 12 Physics Chapter 14 notes. This would help them to gain confidence during preparation and help them in realising their desired goals.

Click on the below links to view exercise-specific questions and solutions for Class 12 Physics Chapter 14 notes:

• Class 12 Physics Chapter 14: Exercises – Questions and Solutions

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NCERT Exemplar Class 12 Physics

Physics is more of an application-based subject. One learns to apply concepts and theories in all the given numerical questions in Physics only if the entire chapter is understood in a better way with  conceptual clarity which comes in handy while solving tricky and advanced level questions.  . Hence, NCERT Exemplar Class 12 Physics covers all the key points and the summary related to the chapter before taking students to the exercise section. As a result,  students can recall the important points easily and make them revise naturally. So students are advised to refer to Exemplar from Extramarks website and enjoy the process of learning conveniently and effortlessly at their own pace. 

These books have proved to be quite useful for students preparing for their high school exams as well as competitive examinations. Students can find challenging questions comparatively easier once they start solving problems from the NCERT Exemplar. The experienced subject matter experts design all the questions in the subject of Physics after going through the latest CBSE curriculum and its examination pattern.This encourages the students to master the topic and increases their confidence in achieving a higher grade. Thus, ensuring students in all aspects of their preparation and continue to climb the ladder of success.

Students can get NCERT Exemplar Class 12 Physics from the Extramarks website by registering on it. Moreover, they can also look for Class 12 Physics Chapter 12 notes on the official website. Both the Exemplar and the notes are genuine and authentic resources and students can rest assured of getting  good grades. The challenging and difficult questions covered in the book help students to develop and strengthen critical and analytical thinking and encourage the student to master the topic.s.

Key Features for Class 12 Physics Chapter 14 notes

A planned and structured study always gives better results. . Hence, Class 12 Physics Chapter 14 notes help students to study effectively by setting realistic goals on a daily basis. The key features are as follows: 

• Students can find well-planned and structured schedules to analyse which chapter to read first and which next. This will help them to manage their time judicially. .
• They can find key points highlighted and easy-to-understand notes, which will help them to learn at a fast pace and achieve more in less time.  
• After referring to Class 12 Physics Chapter 14 notes, students will be able to understand all the vital concepts of the chapter ‘Semiconductor Electronics: Materials, Devices and Simple Circuits’, aiding them  to solve the different kinds of problems of varying difficulty levels confidently..
• Now that you have a complete idea of the entire syllabus, it’s a lot easier to score better marks and in case you require any assistance to step up your preparation with extra study material, you may register yourself at Extramarks official website because it has its own repository of resources which students can’t say no to. Be an early bird and make the most of it.