12th Class Physics Chapter 2 notes
Chapter Name :-
Electrostatic potential and capacitance
Electric potential: -
The ratio of the work done in bringing a positive test
charge from infinity to a point inside the electric field and the test charge is
called electric potential at that point. It is denoted by V.
Let W be the work done in bringing a positive test charge q0 from infinity to a
point P inside the electric field. So by the definition of electric potential
(V=q0 W )
The unit of electric potential is joule/coulomb or volt. and the dimensional
formula is [ML2T -3A-1]. Electric potential is a scalar quantity.
Electric potential difference: -
The ratio of the work done in bringing a
positive test charge from one point to another point within the electric field and
the test charge is called the electric potential difference between those points.
Let if these points are A and B, then the electric potential difference
(VA −VB =q0 W)
Potential gradient: -
The rate of change of potential with respect to distance
in an electric field is called potential gradient. Potential gradient is a vector
quantity. Its direction is from low potential to high potential. Its unit is
volt/meter or newton/coulomb.
potential gradient= dV/dx
E= - (dV/dx)
,This is the equation relating the potential gradient and the intensity of the
electric field.
, Equipotential surface: -
It is a surface located in an electric field on which
the electric potential is the same at every point. This type of surface is called
equipotential surface.
No work is done in moving a charge from one point to another on the
equipotential surface.
Work done in rotating an electric dipole in a uniform electric field
:-
Let an electric dipole XY be placed parallel to the electric field E.
When it is rotated through an angle θ, the electric dipole moves to the X'Y'
position. Then the work done in moving the charge +q to X' and -q to Y' of the
electric dipole is
W = work of +q charge + (work of -q charge)
W = qE (ℓ – ℓcosθ) + qE (ℓ – ℓcosθ)
W = qEℓ(1 – ℓcosθ) + qEℓ (1 – ℓcosθ)
W = 2qℓ × E (1 – ℓcosθ)
From the formula of electric dipole p = 2qℓ
W=PE(1−ℓcosθ)
Electron volt: -
Chapter Name :-
Electrostatic potential and capacitance
Electric potential: -
The ratio of the work done in bringing a positive test
charge from infinity to a point inside the electric field and the test charge is
called electric potential at that point. It is denoted by V.
Let W be the work done in bringing a positive test charge q0 from infinity to a
point P inside the electric field. So by the definition of electric potential
(V=q0 W )
The unit of electric potential is joule/coulomb or volt. and the dimensional
formula is [ML2T -3A-1]. Electric potential is a scalar quantity.
Electric potential difference: -
The ratio of the work done in bringing a
positive test charge from one point to another point within the electric field and
the test charge is called the electric potential difference between those points.
Let if these points are A and B, then the electric potential difference
(VA −VB =q0 W)
Potential gradient: -
The rate of change of potential with respect to distance
in an electric field is called potential gradient. Potential gradient is a vector
quantity. Its direction is from low potential to high potential. Its unit is
volt/meter or newton/coulomb.
potential gradient= dV/dx
E= - (dV/dx)
,This is the equation relating the potential gradient and the intensity of the
electric field.
, Equipotential surface: -
It is a surface located in an electric field on which
the electric potential is the same at every point. This type of surface is called
equipotential surface.
No work is done in moving a charge from one point to another on the
equipotential surface.
Work done in rotating an electric dipole in a uniform electric field
:-
Let an electric dipole XY be placed parallel to the electric field E.
When it is rotated through an angle θ, the electric dipole moves to the X'Y'
position. Then the work done in moving the charge +q to X' and -q to Y' of the
electric dipole is
W = work of +q charge + (work of -q charge)
W = qE (ℓ – ℓcosθ) + qE (ℓ – ℓcosθ)
W = qEℓ(1 – ℓcosθ) + qEℓ (1 – ℓcosθ)
W = 2qℓ × E (1 – ℓcosθ)
From the formula of electric dipole p = 2qℓ
W=PE(1−ℓcosθ)
Electron volt: -
