Class 12th – Electron theory of Electrification | Electric Charges and Fields | Tutorials Point

Summary

This educational transcript delves into electron theories of electrification, explaining the atomic structure with a nucleus carrying a positive charge balanced by electrons' negative charge, resulting in a net charge of zero. It highlights the fundamental charge, or the charge of a single electron, as a key concept, measured in Coulombs. The script explores the exchange of electrons during processes like rubbing, which leads to objects becoming positively or negatively charged. It emphasizes that only electrons, due to their light mass, are responsible for electrification, not protons. The summary concludes with the impact of charging on an object's mass, noting that a negatively charged object gains mass from additional electrons, while a positively charged object loses mass as electrons depart.

Takeaways

• 🔬 Atoms consist of a positively charged nucleus and negatively charged electrons orbiting around it, resulting in a net charge of zero.
• 🚀 The fundamental charge, or the charge of a single electron, is a critical concept, denoted as 'e' and measured at 1.6 x 10^-19 Coulombs.
• ⚖️ The mass of an atom changes when it becomes charged; gaining electrons (negative charge) increases mass, while losing electrons (positive charge) decreases it.
• 🌐 The universe's net charge is zero due to the balance of equal numbers of protons and electrons in all atoms.
• 🔋 The process of electrification involves the transfer of electrons between objects, leading to one object gaining electrons (negative charge) and the other losing them (positive charge).
• ❌ Protons, being much heavier than electrons, do not typically move between atoms, making electrons solely responsible for electrification.
• 💡 The concept of charging by material transfer is essential; a body becomes negatively charged by gaining electrons and positively charged by losing them.
• 🔑 The electron's lightweight nature makes it the preferred particle for nature to move, influencing the charge state of objects.
• 📚 Understanding electron theory is crucial for grasping the basics of electricity and the behavior of different materials in electrical contexts.
• 📈 The script also hints at upcoming topics, such as the classification of materials into conductors, insulators, and semiconductors, and their electrical properties.

Q & A

What is the net charge of an atom?

The net charge of an atom is zero because it consists of an equal number of electrons with negative charges and protons with positive charges in the nucleus.

What is the fundamental charge?

The fundamental charge is the charge on one electron, which is the smallest unit of electric charge. It is 1.6 x 10^-19 Coulombs and is represented by the symbol 'e'.

Why are protons not exchanged during electrification processes?

Protons are not exchanged during electrification processes because they are located in the nucleus of the atom and are much heavier than electrons. The mass of a proton is 1837 times that of an electron, making it less mobile and less likely to be transferred between atoms.

How does the mass of an object change when it becomes charged?

When an object becomes negatively charged, its mass increases because electrons (which have mass) are added to it. Conversely, when an object becomes positively charged, its mass decreases as electrons are removed from it.

What is the role of electrons in the process of electrification?

Electrons are solely responsible for electrification. They can be transferred between atoms, leading to an excess (negative charge) or deficiency (positive charge) of electrons in a material.

What happens during the process of rubbing two objects together?

When two objects are rubbed together, there is a transfer of electrons from one object to another, resulting in one object becoming negatively charged (excess electrons) and the other becoming positively charged (deficiency of electrons).

Why are electrons considered lightweight in comparison to protons?

Electrons are considered lightweight because their mass is significantly smaller than that of protons. This makes it easier for electrons to move between atoms, which is why they are involved in the process of electrification.

What is the significance of the number 1.6 x 10^-19 Coulombs in the context of the script?

The number 1.6 x 10^-19 Coulombs represents the charge of a single electron, known as the fundamental charge. It is a standard measure used in physics to describe the magnitude of electric charge on subatomic particles.

How does the presence of an electron affect the charge of an atom?

The presence of an electron contributes to the negative charge of an atom. If an atom gains an extra electron, it becomes negatively charged, and if it loses an electron, it becomes positively charged.

What are the two types of charges that can result from the transfer of electrons between atoms?

The two types of charges that can result from the transfer of electrons between atoms are positive charge, which occurs when an atom loses electrons, and negative charge, which occurs when an atom gains excess electrons.

What is the relationship between the mass of an electron and the change in mass of a body when it becomes charged?

The mass of an electron is 9.1 x 10^-31 kg. When a body becomes charged, its mass changes due to the addition or removal of electrons. If a body gains electrons, its mass increases, and if it loses electrons, its mass decreases.

Outlines

00:00

🔬 Electron Theories and Atomic Structure

This paragraph delves into electron theories of electrification, explaining that particles carry electric charges. It describes the atomic structure, with a nucleus carrying a positive charge and electrons orbiting around it with a negative charge. The net charge of an atom is zero due to an equal number of protons and electrons. The fundamental charge, or the charge on one electron, is identified as the smallest unit of charge, denoted as 'e' or -/+ 1.6 x 10^-19 Coulombs. The paragraph emphasizes that electrons, being lighter than protons, are more mobile and are responsible for the transfer of charge during processes like rubbing, which can result in an object becoming positively or negatively charged. The concept that the universe's net charge is zero is also introduced.

05:00

🌐 Electron Movement and Charge

The second paragraph focuses on the movement of electrons as the cause of electrical charge. It explains that while protons are heavier and less mobile, electrons are light and can be easily transferred between atoms, leading to either a positive or negative charge. The paragraph clarifies that protons rarely move between atoms due to their significant mass compared to electrons. It also discusses the concept that charging a body involves the transfer of electrons, which affects the mass of the body. Specifically, when a body becomes negatively charged, its mass increases due to the addition of electrons, and when it becomes positively charged, its mass decreases due to the loss of electrons. The mass of an electron is provided as 9.1 x 10^-31 kg, highlighting the significance of electron movement in the process of electrification.

10:01

📚 Charging and Mass Relationship

The final paragraph discusses the relationship between charging a body and the change in its mass. It reinforces the idea that charging involves the transfer of electrons, which in turn affects the mass of the object. The paragraph provides a clear explanation that a negatively charged body has gained mass due to the addition of electrons, while a positively charged body has lost mass due to the loss of electrons. The importance of understanding this relationship is emphasized, as it is fundamental to grasping the principles of electricity. The paragraph concludes with a note on the upcoming discussion about categorizing materials into conductors, insulators, and semiconductors, and how they behave in the context of electricity.

Keywords

💡Electron

Electrons are subatomic particles that orbit the nucleus of an atom and carry a negative electric charge. They are fundamental to understanding electrification and the transfer of charge between materials. In the script, it is mentioned that electrons are the smallest in diameter, mass, and electric charge, and that the net charge of an atom is zero due to an equal number of protons (positively charged) and electrons. The concept is crucial as it explains the process of charging objects by either gaining or losing electrons.

💡Nucleus

The nucleus is the central part of an atom, containing protons and neutrons, and is where the majority of an atom's mass is concentrated. It carries a positive charge due to the presence of protons. In the script, the nucleus is described as being separated from the atom, carrying a positive charge, which contrasts with the negatively charged electrons orbiting around it, thus maintaining the atom's neutral charge.

💡Proton

Protons are subatomic particles found in the nucleus of an atom, carrying a positive electric charge. They are heavier than electrons and are responsible for the positive charge of the nucleus. The script explains that the number of protons in an atom is equal to the number of electrons, thus balancing the charges and resulting in a net charge of zero for the atom.

💡Net Charge

The net charge of an object is the sum of all its positive and negative charges. If the total positive charge equals the total negative charge, the object is considered electrically neutral. The script emphasizes that atoms, and by extension molecules and materials, are electrically neutral because they contain an equal number of protons and electrons, each with opposite charges that cancel each other out.

💡Fundamental Charge

The fundamental charge, also known as the elementary charge, is the electric charge carried by a single proton or, equivalently, the negative of the charge carried by a single electron. The script specifies that the charge on one electron is the smallest unit of electric charge, denoted as 'e', and is approximately 1.6 x 10^-19 Coulombs. This concept is foundational in understanding the quantization of charge in materials.

💡Electrification

Electrification refers to the process of charging an object by either gaining or losing electrons. The script discusses how objects become charged through processes like rubbing, where there is an exchange of electrons between objects. This exchange results in one object becoming negatively charged (excess electrons) and the other positively charged (deficiency of electrons).

💡Charge Carrier

In the context of the script, a charge carrier refers to the particles that carry electric charge, specifically electrons. The script explains that charge is always carried by material, and since electrons are the lightest and most mobile particles, they are the primary charge carriers. This concept is essential for understanding how objects become charged and how electric currents are formed.

💡Conductors, Insulators, and Semiconductors

These are categories of materials based on their ability to conduct electric current. Conductors allow electric current to flow easily, insulators do not, and semiconductors have properties between the two. The script mentions that these categories will be discussed in further detail, indicating their importance in understanding how different materials interact with electric charge.

💡Rubbing

Rubbing, as mentioned in the script, is a common method of transferring electrons from one material to another, leading to the electrification of the objects involved. The process involves friction, which can cause electrons to move from one object to another, resulting in one object becoming negatively charged and the other positively charged.

💡Charge and Mass Relationship

The script explains that there is a relationship between the charge on an object and its mass. When an object becomes negatively charged, it gains electrons, and its mass increases. Conversely, when an object becomes positively charged due to the loss of electrons, its mass decreases. This concept is important for understanding the physical implications of charging processes.

Highlights

Atoms consist of a nucleus and electrons, with the nucleus carrying a positive charge and the electrons carrying a negative charge.

The net charge on an atom is zero due to an equal number of protons and electrons.

Electrons are the smallest in diameter, mass, and electric charge, representing the fundamental charge.

The charge on one electron is known as the basic charge, which is 1.6 x 10^-19 Coulombs.

The universe's net charge is zero because atoms and molecules are composed of equal numbers of protons and electrons.

Electrification occurs through the exchange of electrons, not protons, due to the latter's immobility in the nucleus.

The mass of an electron is very small, making it easier for nature to move electrons rather than protons during electrification.

The process of rubbing can cause a tug-of-war between electrons, leading to a transfer of charge and electrification.

An excess of electrons results in a negative charge, while a deficiency results in a positive charge.

The movement of electrons is responsible for the electrification process, not the movement of protons.

To make a particle positively charged, electrons must be removed from it.

The electron theory explains that charge is always carried by material, specifically electrons.

Charging a body results in a change in mass; a negatively charged body has increased mass due to the addition of electrons.

A positively charged body has decreased mass because electrons have left the body.

The mass of an electron is 9.1 x 10^-31 kg, which is extremely light.

Understanding the electron theory clarifies the fundamentals of electricity.

In the next class, the focus will shift to categorizing materials into conductors, insulators, and semiconductors and their behaviors.

Transcripts

to review study electron theories of

electrification we have studied that

some particles are carrying electric

charges and at the same time there are

researchers going on what happens inside

an atom so in an atom there is one

nucleus and there are electrons around

it it was formed when the nucleus was

separated from the atom we found it is

carrying positive charge so the net

charge on the atoms is zero net charge

on atom is zero and this nucleus is

positive if net charge is zero and

nucleus is positive that means all these

particles which we are separated are

carrying negative charge so all these

electrons are carrying negative charge

now when the study of electron was done

it was found that since this is zero

there are equal number of electrons

equal to the charges which are carrying

positive charge and we found that these

particles are known as protons so equal

number of electrons and protons are

present in an atom electrons are

carrying negative and this is carry

positive and this is what we write every

atom consists of equal number of

electrons in the orbits which have

negative charges and equal number of

protons in the nucleus which have

positive charges okay now we could not

get any particle smaller than neutral

and smaller than electron this is

smallest

in diameter smallest in mass and

smallest in electric charge so the net

charge or one electron is the minimum

charge and this makes the answer of one

a very important question which is

fundamental charge answer the charge on

one electron is f1

little charge okay fundamental charge

what is basic charge the charge on one

electron is known as basic charge and

how much it is our standard unit of

charge is Coulomb and which is a very

large unit but charge on one electron is

1.6 into 10 to the power minus 19

Coulomb because we need it frequently we

have given it a symbol small e now where

we can also write it negative and

positive that is minus e and plus C for

protons

okay then net charge on the atom

remember net charge on the atom is zero

because there are equal number of

protons and electrons if adam has got

charged zero then with the atoms

molecules are made zero charge with the

molecules any material is made zero

charge with the material our complete

universe is made so the net charge of

the complete universe is 0 because the

next charge effective is 0

ok now whenever there is a process of

rubbing or any other process we have the

exchange of electron how this exchange

happens and how this does not happen if

I take this there is a lot of space

between electrons like this and I put

another object on it so that object

electrons go like this now if I lift it

like this straight then there is no

problem but if I want to rub it rub it

means I want to move it like this then

there is a tug-of-war between the two

and what will happen either this will

break or this will break from this atom

and this is exactly what happens when I

put a chalk here when I put an ink here

and I rub it if I place it like this

lift nothing will happen but the moment

I rub it one or the other electron will

break and there will be excess electron

on one item and there will be loss of

electron in the other atom now if there

is a excess electron the excess of

electron that gives the negative charge

to that particular particle the loss of

electron creates a positive charge the

deficiency of electron makes positive

charge on that particle so if anybody

has got negative charge or particle

charge the responsibility is going on to

electron it is either excess of electron

or it is loss of electron but negative

or positive both are due to motion of

electron you can ask why why proton is

not exchanged if a proton goes to

another atom then that we get positively

charged but practically it does not

happen because proton is in the nucleus

and outside it is full of electrons

electrons number two electrons are light

their mass is very less and it is easy

to move them you all know the energy we

have half MV Square this M mass if

nature has to make negatively charged

particle there are two methods remove

this + or add one electron so nature

will choose adding the electrons because

electron is lightweight and it is very

easy to connect electrons electrons are

outside they are light therefore a very

small energy make them able to shift

from one atom to the other item

therefore it is only and

only electron which is responsible for

electrification and this thing I would

like to write here that it is only

electrons okay

it is only electron

which is responsible for electrification

and what I told you why not proton

the answer is proton is not mobile

due to its heavy mass

how heavier is the proton so proton is

1837 times heavier then electrons then

nature will always choose a lightweight

electron to be moved so it's only

electron which is responsible whether a

particle is getting positive charge

negative charge so remember when I asked

you how can we make this particle

positive you will not say that we will

shift certain positive charge to it what

will be your answer we will take out

some electron from it this will become

positively charged this is the method to

make any object as positively charged

particle okay so this is electron theory

all the seven points and you can

remember it seven number is not

important you should remember all the

points and if you remember all these

points then it will make all your

electricity very clear okay so after

this electron theory we will study what

are the effects one thing I would like

to add here before closing that will

there be any change in the mass when a

body is getting charged if this is carry

this is not charged now this is carrying

charge is there any change in its months

it appears that there is no change in

the mass but what does electron theory

says it says it will get negatively

charged only if some electrons have

entered on it this is a very very

important thing unless an electron comes

and sits on it this will not get

negatively charged we cannot give charge

without bringing a material with the

name electron so remember always charge

is always carried by material so if you

make it negatively charged one electron

has come from outside sit on it if you

get it positively charged one material

named electron has gone out of it now

this material is going out and you

material is coming in will there be any

change in the mass of course there will

be a change that means whenever we

charge a body there is certain a change

of mass okay no neutral neutral if we

give it negative charge what will

happens to its mass will it increase or

decrease yes the answer is it will

increase why negative means some excess

electron have gone on it and they will

increase its mass okay if a body gets

positive charge when we rub a glass it

become positively charged what happens

to its mass very simple answer how it

has become positively charged some

electrons have gone out if electrons

have gone out its mass has decreased so

remember negatively charged body

whenever it goes from zero charge to -

charge the mass increases and whenever

it become positively charged the mass

decreases and this we can count if we

know mass of a electron then we can

always count what is the change in the

mass okay so this is I should write it

charged mass relation so I will make a

note for you and you understand zero to

positive charge how it is made electron

leave the body

must decrease and if you want to know

mass of electron which you will see in

nucleus 9.1 10 to the power minus 31 kg

it is such a light so this is charging

oscillation okay so now in the next

class we will see how we divide the

different material around us into

different categories what we call

conductors insulators semiconductors and

how they behave