An electron is a subatomic (smaller than an atom) light particle that carries a single unit of negative electricity, represented as - e. Electrons can either be free (meaning not attached to the atom) or bounded with the nucleus. The charge of the electron is equal to the magnitude of the elementary charge (e) however, holding a negative sign (-e), the value of the basic unit of charge or elementary charge is 1.6 x 10-19 C. Therefore,
It is one of the important constants of nature.
The charge on a single electron (e) is regarded as the unit electrical charge. It is designated as a negative polarity. The charge on an electron is equal, however, opposite to the positive charge on a proton or hole.
Electrons have a mass of 0 amu (atomic mass unit) when they orbit the nucleus and have a charge of -1.
The invariant mass of the electron is given by,
Which is a very small value.
Here, the invariant mass is the rest mass mass or the mass of a stationary electron.
In atomic mass units (amu), the mass of an electron is given by,
In physics, eV stands for electron volt and it is the amount of kinetic energy gained by an electron while accelerating from rest position through an electric potential difference of one volt in vacuum.
Electron volt is the unit of energy generally used in atomic and nuclear physics which is equal to the energy gained by an electron or a charged particle carrying unit electronic charge when the electrical potential at the electron increases by 1 Volt.
Where value of 1 erg = 10-7 Joule
Mass of an electron in eV or electron volt is this mass corresponding to a rest energy given by,
The quantization of electric charge is the property by virtue of which all free charges are an integral part of a basic unit of charge represented by e. Therefore, the charge q of a body is given by,
Where n is any integer, positive or negative. The fundamental charge is the charge that an electron or proton carries, by convention, the charge on an electron is negative. Therefore, charge on an electron is written as (e -1) while the charge on proton is (+e).
The value of the basic unit of elementary charge is given by,
This is one of the fundamental constants used in physics.
If a body carries n1 electrons and n2 protons,then total charge on the body will be:
As n1, n2 are integers so their difference must also be an integer. Hence the charge on any body is an integral multiple of e.
The SI unit of charge is coulomb or C.
The CGS (centimeter-gram-second) unit of charge is 1 electrostatic (e.s.u) of charge or stat charge.
Another unit of charge is one electromagnetic unit (e.m.u) of charge, where
Any charged body or charged particle can possess charge equal to +/- e , +/- 2e, +/- 3e, +/- 4e and so on, i.e., the possible value of charge for one electron will be given by.
Taking the equation: q = ne (putting n = 1), we get,
1. Write properties of electron
All matter consists of atoms that, in turn, contains protons, neutrons and electrons. Out of these three, electrons are the subatomic particles and they are incapable of being broken and they have three fundamental attributes:
Spin: They spin about an axis in a way similar to that of planets.
Mass: The rest mass of an electron is 9.1 x 10 ^ - 31 kg or 5.489 x 10 ^ - 4 amu.
Charge: Electrons are negatively charged in nature and have an electric charge of 1.6 x 10^-19 C, which is used as a standard unit of charge for subatomic particles.
2. What will happen to the mass of an electron if it travels with the velocity of light?
Since the electrons have a stationary or rest mass as 9.1 x 10 ^ - 31. However, when an electron starts moving with the velocity of light that means the speed of electron (v) becomes equal to the speed of light (c) . The mass of the electron would start varying and such variations would be infinite.
3. Write the value of mass of an electron in grams.
The mass of an electron in kg is 9.1 x 10 ^ - 31 kg. Since 1 kg = 1000 g
Therefore, the mass of an electron in grams is 9.1 x 10 ^ -28 g.