Churn, Learn & Earn
Archive for June, 2011
What is resistance and reason for it?
Jun 30th
You must have knowledge of current. As current is the charge per unit time.
Resistance is the obstruction offered to the flow of current.
Reason: As charge (electrons) flow through the wire (conductor), electrons collide with the walls of the conductor and they also collide with each other. Due to this collision, obstruction occurs and this is called resistance.
Let us understand the concept of resistance with a common daily life experience:
Suppose, you are walking at a place where there is no person, it means you are free to move. Now suppose you are moving at delhi or mumbai railway station, then what will happen? You will face lots of people and you will now face obstruction for your movements. This is basically resistance.
IAS preliminary exam new pattern
Jun 29th
Many of us want to appear in the prestigious exam and one of the most difficult exam called “civil services”.
Let us discuss about it:
To clear civil services, one has to pass to three steps:
a) Preliminary exam
b) Main exam (for candidates who clear preliminary exam)
c) Interview (for candidates who clear main exam).
Today I will discuss about the preliminary exam only:
From 2011, the pattern and syllabus of preliminary exam of civil services is going to be changed.
The Preliminary Examination will consist of two papers of objective type carrying a maximum of 200 marks for each paper.
Paper 1 More >
Shaheed Bhagat Singh college of Engineering and technology Ferozepur
Jun 29th
Name of the Institute: Shaheed Bhagat Singh College of Engineering & Technology is situated in the city Ferozepur (Punjab) of India.
Affiliated with: Punjab Technical University (PTU), Kapurthala
Approved by: All India Council for Technical Education (AICTE), New Delhi.
Courses offered: More >
Non polar dielectrics
Jun 20th
In the last article, I have discussed the dielectrics and polar dielectrics. Today let us discuss the non-polar dielectrics:
Non-polar Dielectrics or Molecules. If the centre of gravity of positive charges coincides with the centre of gravity of negative charges then the dielectric is called non-polar dielectric.
Example. H2, N2 etc.
Thus, a non-polar dielectric has a zero electric dipole moment In the presence of electric field, the charge centres get displaced and dielectric or molecule is then said to be polarized and therefore dielectric acquire an induced dipole moment in the direction of the field.
Note : After reading this article, you will be able to answer the following questions:
What are non-polar dielectrics,
What are non- polar molecules,
Write the examples of non-polar dielectric materials,
Why non-polar molecules have zero dipole moment
Dielectrics and their types
Jun 20th
DIELECTRICS
Dielectrics are the materials which do not contain free charges for conduction.
Thus, dielectrics are basically insulators as insulators do not conduct electricity through them. But, dielectrics, contain positive and negative charges which are bounded together and these charges could be effected by
the electric field. The main function of dielectric is the charge storage.
POLAR AND NON-POLAR DIELECTRICS
An atom contains a positive charge in the nucleus and negative charge (electrons) orbitting around the nucleus. The positive as well as the negative charges can be considered to be concentrated at a point. The point at which the positive charge can be assumed to be concentrated is termed as the centre of gravity of the positive charge. Similarly, the point at which the negative charge can be assumed to be concentrated is termed as the centre of gravity of the negative charge. Now we can define the polar and non-polar dielectrics as :
Polar Dielectrics or Molecules: More >
Electric Field Intensity Due To A Point Charge
Jun 18th
Electric Field Intensity Due To A Point Charge
Suppose we have to calculate electric field intensity at any point P due to a point charge q at O, where OP= r.
Consider a small positive test charge q0> at P.
According to Coulomb’s law, force at P is
F = 1/4Пεo qq0/r2 ar
where ar is unit vector directed from q towards q0.
As E = F/q0
Therefore by putting value of F in above equation, we get
E = 1/4Пεo q/r2 ar More >
ELECTRIC FIELD INTENSITY
Jun 18th
ELECTRIC FIELD INTENSITY
It is defined at any point as the force experienced by unit positive charge placed at that point.
The electric field intensity at any point is the strength of electric field at that point.
If F is the force acting on a test charge + q0 at any point, then electric field intensity at this point is given by
E = F/q0
Electric field intensity is a vector. The direction of E is the same as the direction of F that is E is along the direction in which the test charge + q0 would tend to move.
The S.I. unit of electric field intensity is newton per coulomb.
Physical Significance More >
Coulomb’s law and its limitations
Jun 15th
COULOMB’S LAW
Statement. The force of interaction between two stationary point charges q1 and q2 is directly proportional to the product of the charges and inversely proportional to the square of the distance r between them.
That is,
F α q1q2/r2
If the charges are placed in vacuum, then
F = 1/4Пεo q1q2/r2
where 1/4Пεo is a proportionality constant.
εo is the permittivity of free space = 8.85418 x 10-12 C2 /Nm2 or Farad/m
Definition of coulomb: More >
CHARGE DISTRIBUTIONS
Jun 10th
CHARGE DISTRIBUTIONS
There are three types of charge distributions :
a) Linear Charge Distribution. In this distribution the charge is distributed uniformly along a line in a straight line or circumference of a circle. This is represented by λ, the linear density of charge, which is equal to charge per unit length.
λ =dq/dl
Where dq is a small amount of charge in small length dl.
It is measured in C/m.
b) Surface Charge Distribution. More >