Chapter 1: Electric Charges and Fields
NCERT Class 12 Physics, Part I, Chapter 1. 9 lessons, 18 narrated 3D videos, 11 simulations and 18 quiz questions, following the textbook section by section.
- Electric charge and its propertiesOn a dry winter day, pull off a synthetic sweater in a dark room. You hear crackles and may even see tiny sparks. Run a plastic comb through dry hair, and it picks up…
- Coulomb’s lawIn 1785, Charles Augustin de Coulomb measured the force between two small charged metal spheres. He used a torsion balance: the force twists a fine wire, and the angle…
- Forces between multiple chargesCoulomb’s law tells us the force between two charges. But what if there are three charges, q₁, q₂ and q₃? What is the total force on q₁?
- Electric fieldA charge Q sits at the origin. Put a small test charge q at a point P, a distance r away. By Coulomb’s law it feels a force F equals k Q q over r², along r̂.
- Field lines and electric fluxDrawing a field arrow at every point gets messy fast. Faraday had a better picture: electric field lines. A field line is a curve whose tangent at every point gives the…
- The electric dipoleAn electric dipole is a pair of equal and opposite charges, plus q and minus q, a small distance 2a apart. Its total charge is zero, but its field is not zero, because…
- Charge distributions and Gauss’s lawCharge is quantised. But a charged body carries so many electrons that it is far easier to treat the charge as smeared out smoothly, like paint, rather than as separate…
- Applications of Gauss’s lawAn infinitely long straight wire carries a uniform charge λ per metre. By symmetry, its field must point straight out from the wire, at right angles to it, and must have…
- Charging by inductionThis topic, charging by induction, is beyond the current NCERT syllabus. It was in the older textbook, and it is still useful, for example for competitive exams.