Unit 1: Electrostatics (PHYDSM252T)

1. Electrostatic Field and Electric Flux

The Electrostatic Field is the region around a charged particle where another charge experience a force. Electric Flux is a measure of the total number of electric field lines passing through a given area.

2. Gauss's Theorem and Applications

Gauss's Theorem states that the total electric flux through any closed surface is equal to 1/ε₀ times the net charge enclosed by that surface.

Applications:

• Point Charge: Determining the field at a distance r.
• Infinite Line of Charge: Field due to a wire with linear charge density λ.
• Uniformly Charged Spherical Shell and Solid Sphere: Analyzing the field both inside and outside the sphere.
• Plane Charged Sheet: Field due to an infinitely large flat surface.

3. Electric Potential

Electric Potential at a point is defined as the work done in bringing a unit positive charge from infinity to that point. It can be expressed as the negative line integral of the electric field.

4. Potential due to an Electric Dipole

An Electric Dipole consists of two equal and opposite charges separated by a small distance. The potential at any point in the field of a dipole depends on the dipole moment and the distance/orientation of the point.

5. Capacitance and Condensers

Capacitance is the ability of a conductor to store electric charge. A Condenser (Capacitor) is a system of two conductors used to store large amounts of charge and energy.

Types of Capacitors:

• Isolated Spherical Conductor: Capacitance depends on its radius.
• Parallel Plate Condenser: Most common type; capacitance depends on plate area and separation.
• Spherical and Cylindrical Condensers: Used for specific engineering and physical applications.

6. Energy in Electrostatic Field

Energy is required to assemble a system of charges. This energy is stored in the Electrostatic Field itself. The Energy per unit volume (Energy Density) in an electrostatic field is a key concept in electromagnetism.