Physics

• Potential energy is useful in the study of electricity
• A potential energy function can be defined corresponding to the electric force
• Electric potential can also be defined
• The concept of potential relates to circuits
• The Coulomb force is a conservative force
• It is possible to define an electrical potential energy function with the Coulomb force
• Work done by a conservative force is equal to the negative of the change in potential energy
• There is a uniform field between the two plates
• As a charge moves from point A to point B, work is done on it
• The SI unit of energy is Joules (J)
• The electric potential difference ΔV between points A and B is defined as the change in potential energy of a charge q moved from A to B divided by the size of the charge
• Potential difference is not the same as potential energy
• Another way to relate energy and potential difference is ΔPE = qΔV
• Both electric potential energy and potential difference are scalar quantities
• The point of zero electric potential is taken to be at an infinite distance from the charge
• The potential created by a point charge q at any distance r from the charge is
• If charges have the same sign, potential energy is positive
• If charges have opposite signs, potential energy is negative
• When released from rest, positive charges accelerate from regions of high potential to low potential
• When released from rest, negative charges accelerate from regions of low potential to high potential
• Work must be done on negative charges to make them go in the direction of lower electric potential
• The work required to bring q2 from infinity to point P without acceleration is q2V1
• The capacitance of a capacitor is defined as the ratio of the magnitude of the charge on either conductor to the magnitude of the potential difference between the conductors
• The unit of capacitance is the Farad (F)
• The electric field between the plates of a parallel-plate capacitor is uniform
• The potential difference across capacitors in parallel is the same and equal to the voltage of the battery
• The total charge on capacitors in parallel is equal to the sum of the charges on the individual capacitors
• The equivalent capacitance of capacitors in parallel is the sum of the individual capacitances
• The equivalent capacitance of a parallel combination of capacitors is greater than any of the individual capacitors
• Capacitors in series store the same charge
• The equivalent capacitance of a series combination is always less than any individual capacitor in the combination
• The potential difference across each capacitor in a series combination is different and depends on the capacitance of each capacitor
• The charge stored on each capacitor in a series combination is the same