Charging a Body by Induction Method and Coulomb's Law

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Software Engineer at Padandas

Published: 2024-01-01 Last updated: 2024-01-01

Charging a body negatively by using induction method

Take an isolated conductor with insulated stand.
Bring a glass rod rubbed with silk near one end of an isolated conductor.
Connect the remote end of the conductor to the ground with the help of conducting wire. (The process is called grounding or earthing)
Induced free charge (positive charge) is neutralized by the flow of electrons from the earth.
Cut the grounding/earthing and finally remove the glass rod.
The induced bound charge which is negative finally gets distributed throughout the conductor and it is negatively charged.

Charging a body positively by using induction method

Take an isolated conductor with insulated stand.
Bring a glass rod rubbed with fur near one end of an isolated conductor.
Connect the remote end of the conductor to the ground with the help of conducting wire. (The process is called grounding or earthing)
Induced free charge (negative charge) is neutralized by the flow of electrons from the earth.
Cut the grounding/earthing and finally remove the glass rod.
The induced bound charge which is positive finally gets distributed throughout the conductor and it is positively charged.

Conductors

Those materials having free electrons are known as conductors. Due to the presence of free electrons conductors allows easy flow of electric current through them. Example: metals

Insulators

Those materials having all bounded electron are called insulators. Due to lack of free electrons they do not allow the flow of electric current through them. Examples: non-metals

Electric charge per unit area is called surface charge density.

i.e. surface charge density $\sigma = \frac{\text{electric charge(q)}}{area(A)}$

$$\therefore \sigma = \frac {q}{A}$$

Electric charge has a tendency to accumulate at sharp edges, corners and pointed parts to have high surface charge density there. Due to this, the charge can leak by the process of corona discharge.

Difference between electric charge and electric mass

SN	electric charge	SN	electric mass
1	Electric charges are positive as well as -ve.	1	Electric masses are always positive.
2	It is independent of the motion of the charged body.	2	Mass of an object varies relativistically according to the relation $$M=\frac{M_o}{\sqrt{1-\frac{V^2}{C^2}}}$$ where, M_o = mass of the body at rest M = mass of the body while moving without velocity.
3	Electric charge follows quantization condition. $$\text{i.e.} q = \pm ne$$	3	Quantization of mass is unknown yet.
4	The force between two charged can be attractive as well as repulsive according to Columb's law. $$\therefore f = \frac{kq_1q_2}{r^2}$$	4	The force between two masses as given as Newton's law of gravitation is always attractive. $$\therefore f = G\frac{M_1M_2}{r^2}$$