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    Electrostatics II

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    jenish patel
    1) The document discusses electric potential energy and conservative forces. It states that the difference in potential energy between two points is equal to the negative of the work done by a conservative force between those points. 2) It provides examples of conservative forces, including gravitational and electrostatic forces. It gives an equation to calculate the difference in potential energy for a conservative force. 3) The document then discusses electric potential and provides equations to calculate electric potential due to single charges and systems of multiple charges. It also discusses electric potential due to electric dipoles.

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    Electrostatics II

    Uploaded by

    jenish patel
    16 views51 pages
    1) The document discusses electric potential energy and conservative forces. It states that the difference in potential energy between two points is equal to the negative of the work done by a conservative force between those points. 2) It provides examples of conservative forces, including gravitational and electrostatic forces. It gives an equation to calculate the difference in potential energy for a conservative force. 3) The document then discusses electric potential and provides equations to calculate electric potential due to single charges and systems of multiple charges. It also discusses electric potential due to electric dipoles.

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    Electrostatics-II

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    1) The document discusses electric potential energy and conservative forces. It states that the difference in potential energy between two points is equal to the negative of the work done by a conservative force between those points. 2) It provides examples of conservative forces, including gravitational and electrostatic forces. It gives an equation to calculate the difference in potential energy for a conservative force. 3) The document then discusses electric potential and provides equations to calculate electric potential due to single charges and systems of multiple charges. It also discusses electric potential due to electric dipoles.

    Copyright:

    © All Rights Reserved
    Download as PPTX, PDF, TXT or read online from Scribd
    Download as pptx, pdf, or txt
    16 views51 pages

    Electrostatics II

    Uploaded by

    jenish patel
    1) The document discusses electric potential energy and conservative forces. It states that the difference in potential energy between two points is equal to the negative of the work done by a conservative force between those points. 2) It provides examples of conservative forces, including gravitational and electrostatic forces. It gives an equation to calculate the difference in potential energy for a conservative force. 3) The document then discusses electric potential and provides equations to calculate electric potential due to single charges and systems of multiple charges. It also discusses electric potential due to electric dipoles.

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    © All Rights Reserved
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    You are on page 1of 51

    Paper 102

    Electrostatics-II
    Electric Potential Energy
     When a particle moves between points a
    and b under the influence of a force F the
    difference in potential energy DU is equal
    to the negative of the work done Wab by the
    force, i.e.
    U  Wab

     But, remember that this equation is


    applicable only when the force is
    conservative
    Electric Potential Energy
     Now a question is
     What is a conservative force?
     The work done under the influence of such
    a force is independent of the path taken by
    the particle, it depends only on the initial
    and final position
     In other words, work done on a closed path
    under the influence of such a force is zero
    Electric Potential Energy
     Examples of such forces are: gravitational
    force and electrostatic force
     The equation for difference in the potential
    energy under the influence of such a
    conservative force can also be written as
    b  
    U  U a  U b    F  dl
    a
    Electric Potential Energy
    𝞓U > 0
    Homework

    EXAMPLE

    Hint: Apply conservation of energy


    (KE + PE) Before = (KE + PE) After

    Ans. 240 m/s


    The electric potential energy of a system of
    fixed point
    charges at rest is equal to the work that
    must be done by an external agent to
    assemble the system, bringing each charge
    in from an infinite distance where it is also
    at rest.
    Potential difference
    Electric Potential
     This equation for electric potential (V) at
    point P at a distance r from the charge Q
    Q
    VP 
    4 o r

    indicates that the potential due to positive


    charge is positive, that due to negative
    charge is negative
    Electric Potential
     Electric potential at point P due to system
    of n number of charges is given by
    1 qi
    V  V1  V2  V3  ... 
    4 o
    i r
    i
    Electric Potential
     Note that the sum here is an algebraic sum
    and not a vector sum
    1 qi
    V  V1  V2  V3  ... 
    4 o
    i r
    i
    Potential due to an Electric Dipole
     We have already discussed about electric
    dipole
     Two equal and opposite charges (q)
    separated by a finite distance (2a)
    constitute an electric dipole
     Each dipole has a dipole moment (p), given
     
    by p  q2a 
     It’s a vector, directed from negative charge
    to positive charge
    Potential due to an Electric Dipole
     An electric dipole is
    arranged on Y- axis as
    shown in the figure
     An expression for electric
    potential at a point P,
    having coordinates (r, q)
    due to this dipole

    1 p cos 
    V
    4 o r 2
    Potential due to an Electric Dipole
     It is clear that at every
    point on the perpendicular
    bisector of the dipole (X-
    axis), q = 90o
     Therefore, cos q = 0
     And hence, the potential is
    also zero there
    1 p cos 
    V
    4 o r 2
    Potential due to an Electric Dipole
     This means that the electric
    field of the dipole does no
    work when a test charge
    moves from infinity along
    a line in the mid-plane of
    the dipole

    1 p cos 
    V
    4 o r 2
    Potential due to an Electric Dipole
     For a given value of r, the
    potential is maximum
    positive when q = 0o and it
    is maximum negative when
    q = 180o

    1 p cos 
    V
    4 o r 2
    Potential due to an Electric Dipole
     One more important point
    to be noted
     The potential due to an
    electric dipole varies as
    1/r2 and not as 1/r as in the
    case of a point charge

    1 p cos 
    V
    4 o r 2
    Same charges Opposite Charges
    Circuit with two resistances
    Circuit with Internal resistance
    Solution of the
    equation
    Solution of the
    equation

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