physics 2 electric potential

Attendance Roll Call

  • Lewis: Present
  • Ariel: Present
  • Ronald: Present
  • Michael: Present
  • Juan: Present
  • Frankie: Present
  • Kimmy: Present
  • King: Not called
  • Brooke: Present
  • Ali: Present
  • Kamal: Present
  • Ahmed: Present
  • Real: Present
  • Carol: Present
  • Janine: Present
  • Austin: Present
  • Sabah: Present

Classroom Interaction and Homework Review

  • Instructor checks attendance with names listed, confirming presence.
  • Instructor inquires about homework assignments, specifically problem numbers 22, 23, and 24.

Solution Discussion for Homework Problems

  • Homework Problem 22: Finding the Magnitude of Electron’s Initial Acceleration

    • Charge Density: Given as six microcoulombs per meter (bcC/m)

    • Concept of Electric Field: "By symmetry," the electric field direction is derived using Gauss's law.

    • Gauss's Law Recap: ext{Electric flux} = rac{Q_{inside}}{ ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ }} ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ }}

    • Electric field (E) is constant due to symmetry along the cylinder.

  • Deriving Electric Field:

    1. The total charge inside relates to the linear charge density:
    • Q=extlinearchargedensity(extextextextextextextextextextextextextextextextextextextextextextextextextext)imeslQ = ext{linear charge density} ( ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ }) imes l
    1. From Gauss’s law, E = rac{ ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ }} ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ }}
    • Where extextextextextextextextextextextextextextextextextextextextextextextextextextext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } represents epsilon sub zero

  • Electron Acceleration Calculation:

    1. Using the formula F=maF = ma, where ( F ) is determined by F=qEF = qE resulting in (E = rac{ ext{linear charge density}}{2 ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ }}.
    2. Determine the electron's acceleration as
    • a = rac{F}{m} = rac{qE}{m}.

Coulomb's Law and Electric Fields

  • Coulomb's Law Definition:
    • F = k rac{q_1 q_2}{r^2} where
    • F is the force between the charges,
    • kisCoulomb′sconstant(approximatelyis Coulomb's constant (approximately8.99 imes 10^9 ext{ N m}^2/ ext{C}^2),
    • q_1, q_2arethecharges,andare the charges, andr is the distance between them.
  • Direction of Forces:
  • Same charges repel while opposite charges attract.

Finding Directions of Electric Forces on Electrons

  • In the context of electrons, establish force direction based on their negative charge in an electric field.
  • Example: If electron is in a positive field, the force will act in the opposite direction to the electric field.

Additional Homework Problems

  • Problems 23 and 24 involve practical applications regarding cylindrical charge distributions and formula utilization.
  • Problem 23: Find the total charge on a photocopy drum given dimensions and electric field.
  • Problem 24: Calculation involving the electric field at specific radial distances.
  • Conduct visual illustrations to enhance understanding.

Concepts of Electric Potential

  • Definition of Electric Potential Energy
    • ext{Potential Energy} = - ext{Work Done}$$ relating to change in energy involving external forces.
  • Electrical Potential (V):
    • Definition based on work done per unit charge.
    • Measured in units of volts (Joules/Coulombs).
  • Electron Volt (eV):
    • Energy gained by an electron when moving through a potential difference of 1 Volt.
  • For example:
    • An electron moving through one volt acquires 1.6 x 10^-19 Joules.

Practical Applications of Voltage

  • Discussion on how various tools are rated based on volts, such as batteries:
    • Example of AA batteries rated at 1.5 volts, indicating stored energy per coulomb.
  • Understanding electric fields' impact on potential energy movements; shifting of charges in fields can lead to observable currents and voltages in circuits.

Conclusion

  • Recap on significance of Coulomb's law, electric field calculations, electric potential energy definitions, and practical applications in everyday electronic devices and systems.