LN TOPIC 1_Student

• EP025 Electrostatics Overview

• Institution: Kolej Matrikulasi Kejuruteraan Johor

• Instructor: Miss Amalina Shukri

• Key Topics:

  1. Coulomb's Law

  2. Electric Field

  3. Electric Potential

  4. Charge in a Uniform Electric Field

• Practical demonstration of static electricity using the Van de Graaff generator.

Introduction to Electrostatics

• Definition: Electrostatics is the study of electrical charges in a static condition.

• Focus Areas:

  • The influence of one charge on another

  • Forces between charges

  • Area of influence known as the electric field

  • Energy produced and lost during operations involving charges.

Learning Objectives

• At the end of the chapter, students should be able to:a) State Coulomb’s Lawb) Sketch the force diagramc) Apply Coulomb’s Law for a system of point charges.

  • Formula: F = k * (Q1 * Q2) / Where:

    • F = electrostatic force

    • k = Coulomb constant (9 × 10⁹ N m² C⁻²)

    • Q1, Q2 = magnitudes of the charges (in Coulombs)

    • r = separation distance between the charges.

    • Where:

      • F = electrostatic force

      • k = Coulomb constant (9 × 10⁹ N m² C⁻²)

      • Q1, Q2 = magnitudes of the charges (in Coulombs)

      • r = separation distance between the charges.

Coulomb’s Law

• Statement: The electrostatic force (F) between two charges

  • (i) is inversely proportional to the square of the separation distance (r) and,

  • (ii) is directly proportional to the product of the magnitudes of the charges (Q1 and Q2).

• Formula Recap: F = k * (Q1 * Q2) / r²; with k = 9 × 10⁹ N m² C⁻²

Nature of Electrostatic Forces

• The electrostatic force is directed along the line joining the charges:

  • vF12: Force exerted on charge 1 by charge 2

  • F21: Force exerted on charge 2 by charge 1

• Force direction:

  • Attraction occurs between opposite charges

  • Repulsion occurs between like charges.

• Consistent with Newton's third law: F12 = -F21.

Electric Field

Definition

• Electric field (E) is defined as the region of space around an isolated charge where an electric force is e xperienced by a positive test charge placed within it.

Characteristics

• Direction of Electric Field:

  • Positive charges create a field that points outward.

  • Negative charges direct the field inward.

• The electric field is depicted using field lines which provide a visual representation of the force.

Electric Field Strength (E)

• Defined as the electric force per unit positive charge that acts at that point: E = F/q₀

• Units: N/C or V/m

Electric Potential (V)

• Definition: The work done per unit charge to bring a test charge from infinity to a point in an electric field.

• Formula: V = W/q

• Units: Joules per Coulomb (J/C) = Volts (V)

Potential Difference

• Potential difference (ΔV) between points A & B: ΔV = V_B - V_A = W/q

Electric Potential Energy (U)

• Electric Potential Energy (U): Work needed to assemble a configuration of charges.

• Defined as U = qV, where q is the charge and V is the electric potential.

Equipotential Surfaces

• Definition: A surface where all points have the same electric potential.

• Properties:

  • No work is required to move a charge along an equipotential surface.

  • The electric field is perpendicular to the equipotential surfaces.

Charge in a Uniform Electric Field

• Produced by two flat parallel metal plates, one positively charged and the other negatively charged.

• Electric field (E) direction: from positive to negative plates.

• If a charge (e.g., an electron) is released between the plates, it accelerates towards the positive plate due to the electric force (F).

Relationships and Formulas

• F = ma = qE

• Distance and motion equations can be used to describe trajectories.

Conclusion

• In-depth understanding of electrostatics is essential for further studies in physics.

• The next chapter will cover Capacitors & Dielectrics.