Electric Charges and Magnetic Field Flashcards
Electric charge
Property of a matter by which it exerts/experiences electric/magnetic effect.
Eg: Lightning during thunderstorm due to an electric charge
Frictional electricity
electricity developed due to friction between 2 objects
Properties of Electric charge
i)2 types of charges, positive (proton) & negative (electron)
-Represent charge as ‘q’
-Value of 1 e = 1.6 * 10^-19C
-Unit of charge is Coulomb
-mass of e = 9.1 *10^-31kg
ii)like charges repel, unlike charges attract
iii) charges are additive in nature
iv) charges are quantised in nature
what does it mean charges are quantised in nature?
q=+-ne
where e= 1.6 * 10^-19
total charge of a system is an integral multiple of electric charge
Conservation of charges
charges are neither created nor destroyed
or
charges remain constant
Charging by conduction
A body gets charged by touching another charged body with the uncharged body.
Here, the same type of charges are distributed to the uncharged body (diagram)
Why is charging by induction preffered?
a number of bodies can be charged without any loss of charges. Thus induction is more preferred than conduction.
Charging by induction
Charging of an uncharged body by the presence of another charged body is known as charging by induction. Here opposite charges are produced.(diagram)
Coulombs law
Coulombs law gives the force of attraction or repulsion between two charges separated by a distance r.
F= Kq1q2/r^2
Coulombs constant (K)
K=1/4pie epsilan0
=9 * 10^9 Nm^2C^-2
epsilan zero
it is the absolute permittivity
=8.85 * 10^-12 N^-1m^-2C^2
Define 1 Coulomb according to Coulombs law
1C is the charge that when placed at a distance of 1m from another charge of the same magnitude in vacuume experiences a repulsive force of magnitude 9 * 10^9 N
Electric field
it is a space/region surrounded by a charge where another charge can experience a force.
Electric field intensity
strength of an EF at a point
Electric field lines
Imaginary lines/path along which a positive charge travels if it is free to do so
Properties of EF lines
-starts from+ve charge, end at -ve charge
-EF lines never intersect each other
(diagram)
-EF lines form continuose closed loops
-EF lines form continuouse curve without any break
-Closeness of EF lines shows the strength of EF at that point
-Inside a conductor EF is zero
Dipole
two equal and opposite charges seperated by a small distance
Electric flux
total no. of EF lines crossing in normal to a surface is known as electric flux
Gauss’s Theorem
The total electric flux through a closed surface enclosing a charge is equal to 1/epsilan 0 times the magnitude of the charge enclosed. Where epsilan 0 is the permitivity of free space
