This article is a continuation of the revision notes on CBSE Class 12 Physics, Chapter - Electric Charges and Fields. Basic concepts are covered in the Part I. In this part we will focus on some more important concepts like electric fields and electric dipoles.
Electric field due to a given charge is the space around the charge in which electrostatic force of attraction or repulsion due to the charge can be experienced by any other charge.
Source Charge & Test Charge:
The charge which produces electric field is known as source charge.
Charge (generally written as qo) which tests the effect of source charge is called test charge.
Electric Field Intensity:
Electric filed intensity at any point is the strength of electric field at that point. It is defined as the force experienced by unit positive charge placed at that point.
Electric Field Line:
An electric field line is defined as a path, straight or curved in electric field, such that tangent to it at any point gives the direction of electric field intensity at that point
Properties of Electric Field Lines:
• Electric field lines are continuous curves.
• They start from positively charge and end at negatively charges body
• Tangent to the electric filed line at any point gives the direction of electric field intensity at that point
• No two electric field lines intersect each other
• Electric field lines are always normal to the surface of of a conductor
Expression for electric field intensity at a point:
Electric field intensity due to a point charge:
Electric field intensity at any point due to a group of point charges:
Electric field intensity at any point due to a group of point charges is equal to the vector sum of electric field intensities due to individual charges at the same point.
An electric dipole consists of a pair of equal and opposite point charges separated by some small distance.
It is a measure of the strength of electric dipole. The magnitude of dipole moment is given by product of either charge and the distance between them.
It is a vector quantity whose direction is from negative to positive charge.