Definitions [3]
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.
The basic property of matter due to which it experiences electric force and shows attraction or repulsion, is called electric charge.
Key Points
- Thales (≈2500 years ago) observed that amber rubbed with wool attracts light objects like paper and straw.
- William Gilbert (1600) showed that many materials, such as glass, ebonite, and sulphur, also show this effect.
- This attractive property is produced by rubbing (friction); a material showing it is said to be electrified, and the process is called frictional electricity.
- An electrified material possesses electric charge and is therefore called a charged body.
- Electric charge is quantised (q = ±ne, e = 1.6 × 10−19 C); there are two types of charges (positive and negative), as charges repel, unlike charges attract, and the SI unit of charge is coulomb (C).
