Electric Charges and Fields Flashcards
What do you mean by Quantisation of Electric Charge?
q=ne; Charge on any body is the integral multiple of the charge on an electron or proton.
What do you mean by Conservation of Electric Charge?
The total amount of charge in an isolated system remains a constant. Charge can neither be created nor destroyed. Net charge of a system=0.
What do you mean by invariance of Charge?
It states that the value of charge does not change with velocity.
What is Coulomb’s Law?
According to Coulomb’s law, the force of attraction or repulsion between two point charges is directly proportional to the product of the charges and inversely proportional to the square of the distance between them and act along the line joining the charges.
Write the Expression for Force in Coulomb’s Law
REFER NOTE.
What is the value for Permittivity of Free Space?
8.85 x 10^-12 C2/Nm2
What is the value for k (proportionality constant)?
9 x 10^9 Nm2/C2
Write the dimensions of Permittivity of Free Space
REFER NOTE.
Write Coulomb’s Law in Vector Form
REFER NOTE.
Properties of Forces in Coulomb’s Law
The two forces are equal and opposite. (Form action-reaction pair).
They act along the line of joining of the two charges.
It is a conservative force.
It obeys inverse square law.
What is Relative Permittivity of a Medium?
The permittivity of a medium with respect to air or vacuum. The ratio of absolute permittivity of medium to permittivity of free space.
Define one Coulomb.
One coulomb is that charge which when kept in free space at a distance of 1m from an equal and similar charge repels with a force of 9 x 10^9 N.
What do you mean by the Permittivity of a Medium being 81?
It means that the Permittivity of that medium is 81 times that of free space.
What are the differences between Coulomb’s law and Gravitational Law?
- Electrical forces maybe attractive as well as repulsive. Gravitational force is only attractive.
- Electrical forces depends upon the medium. Gravitational force does not depend upon the medium.
State the Principle of Superposition of Charges.
If a system contains a number of interacting charges, the force between two charges is not affected by the presence of the other charges, but the net force acting on a charge is the total vector sum of all the forces due to the all the other charges.
What is an Electric Field?
Region around a charge where another charge can experience a force.
What do you mean by Intensity of Electric Field?
It is the force acting on a unit test charge at that point (of the electric field).
