EEE Dept Engineering Topics List

Image Theory, Point Charges, Example Solved Problems | Electrostatics

Subject and UNIT: Electromagnetic Theory: Unit II: (a) Electric Work Potential and Energy

• The method of images is introduced by Lord Kelvin in 1848.

Subject and UNIT: Electromagnetic Theory: Unit II: (a) Electric Work Potential and Energy

• The two point charges of equal magnitude but opposite sign, seperated by a very small distance give rise to an electric dipole. The field produced by such a dipole plays an important role in the engineering electromagnetics.

Subject and UNIT: Electromagnetic Theory: Unit II: (a) Electric Work Potential and Energy

If the external source is removed then the unit positive charge will be subjected to a force exerted by the fieldp and will be moved in the direction of force.

Electrostatics

Subject and UNIT: Electromagnetic Theory: Unit II: (a) Electric Work Potential and Energy

• The potential decreases as distance of point from the charge increases. This is shown in the Fig. 4.12.1.

Electrostatics

Subject and UNIT: Electromagnetic Theory: Unit II: (a) Electric Work Potential and Energy

• It is seen that, the work done in moving a test charge around any closed path in a static field E is zero. This is because starting and terminating point is same for a closed path.

Electrostatics

Subject and UNIT: Electromagnetic Theory: Unit II: (a) Electric Work Potential and Energy

Key Point : An equipotential surface is an imaginary surface in an electric field of a given charge distribution, in which all the points on the surface are at the same electric potential.

Subject and UNIT: Electromagnetic Theory: Unit II: (a) Electric Work Potential and Energy

This is a standard result and may be used to find potential difference between the points due to infinite line charge.

Subject and UNIT: Electromagnetic Theory: Unit II: (a) Electric Work Potential and Energy

• Consider a uniform volume charge density p v C/m3 over the given volume as shown in the Fig. 4.8.1.

Subject and UNIT: Electromagnetic Theory: Unit II: (a) Electric Work Potential and Energy

Consider uniform surface charge density ρs C/m2 on a surface, as shown in the Fig. 4.7.1

Subject and UNIT: Electromagnetic Theory: Unit II: (a) Electric Work Potential and Energy

• Consider a line charge having density ρL C/m, as shown in the Fig. 4.6.1.

Subject and UNIT: Electromagnetic Theory: Unit II: (a) Electric Work Potential and Energy

1. Concept of Absolute Potential 2. Potential due to Point Charge Not at Origin 3. Potential due to Several Point Charges 4. Potential Calculation When Reference is Other Than Infinity

Concept, Example Solved Problems

Subject and UNIT: Electromagnetic Theory: Unit II: (a) Electric Work Potential and Energy

• Notation : If B is the initial point and A is the final point then the potential difference is denoted as VAB which indicates the potential difference between the points A and B and unit charge is moved from B to A.