Electrostatics — Class 11 Maharashtra HSC Physics revision notes
A 6-page visual revision sheet for Electrostatics, written for Class 11 Maharashtra HSC Physics. Formulas, diagrams and the traps that cost marks, laid out to be read the night before rather than the term before. Free, and it opens inside CapCompass.
Page 1 as PDF
Electrostatics in one look
charge, Coulomb's law, field, Gauss's law and the dipole
Electric charge, the basics
- charging by friction transfers electrons: the gainer turns −, the loser +, equal and opposite
- charge is additive: total is the algebraic sum, sign included, unlike mass it can be negative
- charge is quantized: q = ± ne, e = 1.6×10^-19 C the elementary charge
- not obvious daily since e is tiny: even 1 μ C needs about 6×10^12 electrons
- charge is conserved: never created or destroyed, only transferred
Charging by induction
- conductors let charge move (metals, earth, body); insulators hold it (glass, plastic)
- induction: a charged rod nearby shifts free electrons, near side opposite, far side similar
- rod near, earth it, remove the earth, then the rod: a charge opposite to the rod's stays
Coulomb's law
- scalar form, in vacuum
F = 1/4πε_0q_1q_2/r^2 - Coulomb's constant
1/4πε_0 = 9×10^9 N m^2C^-2 - vector form, force on q_2 due to q_1
F_21 = 1/4πε_0q_1q_2/r_21^2r_21 - in a medium of relative permittivity ε_r
F_med = 1/4πε_0ε_rq_1q_2/r^2
Page 1 of 6. The full sheet, all 6 pages, opens free in the app.
What this Electrostatics sheet covers
- electric charge
- quantization of charge
- Electric charge, the basics
- induction
- Charging by induction
- coulomb's law
- scalar form, in vacuum
- Coulomb's constant
- vector form, force on q_2 due to q_1
- in a medium of relative permittivity ε_r
- Coulomb's law, special cases
- Superposition of forces
- net force on q_0 from many charges
- Electrostatic vs gravitational force
- Similarities
- Differences
- electric field
- defining relation, a vanishingly small test charge
- field of a point charge Q, in vacuum
- field of a point charge, in a medium of dielectric constant K
- between two charged parallel plates, separation d
- Lines of force
- Lines of force of charged shapes
- Conductors in an electric field
- electric flux
- Gauss's law, statement
- flux through any closed surface
- Gauss's law, from Coulomb's law
- electric dipole
- dipole moment
- The electric dipole
- Dipole in a uniform field
- force on each charge
- torque on the dipole
- vector form
- Field of a dipole
- on the axis, r much greater than l
- on the equator, r much greater than l
- linear charge density
- surface charge density
- volume charge density
- Continuous charge distribution
- Symbols
- Traps that cost marks
- Tricks that save time
How CapCompass uses this sheet
These notes are not a standalone PDF. CapCompass plans Physics chapter by chapter against your real exam dates and free hours, and when the plan reaches Electrostatics the sheet opens inside the study block itself — at the page covering the sub-topic that block is on, with the timer still running. Revision arrives at the moment the plan says revise, instead of having to be gone looking for.