Definitions [5]
What are free electrons?
FREE ELECTRONS. Electrons of the outermost orbit of a solid, which can easily leave the atom and become free to move inside the solid are called FREE ELECTRONS
What do you mean by conservation of charges?
According to the Law of conservation of charge
“When two different bodies are rubbed together, both bodies get charged equally but with charges of the opposite kind.” Thus, the total charge of two bodies before and after rubbing remains the same.
Example: When an ebonite rod is rubbed with fur, the electrons from the fur are transferred to the ebonite rod and therefore the ebonite rod becomes negatively charged (due to gain of electrons), while the fur becomes equally positively charged (due to deficit of a same number of electrons). As the same no. of electrons are, exchanged by the ebonite rod and fur, the magnitude of charges main same but with opposite sign.
An electric charge which can be considered to exist at a single point is called a point charge.
A unit positive charge used to test the strength of electric fields is called a test charge.
The basic property of matter due to which it experiences electric force and shows attraction or repulsion, is called electric charge.
OR
The fundamental property of subatomic particles that gives rise to the phenomenon of experiencing force in the presence of electric and magnetic fields is called electric charge.
- Positive charge: Deficiency of electrons
- Negative charge: Excess of electrons
- SI unit: Coulomb (C)
- Dimension: [M0L0T1A1]
Key Points
- Electric charge is additive — the total charge of a system is the algebraic sum of all charges in it.
- Example: A system with +5 C and −2 C has a net charge of +3 C.
- Electrostatic forces between two point charges obey Newton's Third Law — action and reaction are equal and opposite.
