Electrostatics — Class 12 Maharashtra HSC Physics revision notes
A 6-page visual revision sheet for Electrostatics, written for Class 12 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
Gauss's law at work, then potential, dielectrics and the capacitor
Extending Gauss's law
- ointE· ds=q_enc/ε_0, used for three symmetric shapes
- choose a Gaussian surface to match the symmetry: sphere, cylinder, pillbox
- flux from geometry = flux from Gauss's law: solve for E, no integration
- wire falls as 1/r, shell as 1/r^2 outside, the sheet does not fall
Field of a uniformly charged spherical shell
- outside the shell, r>R
E=1/4πε_0q/r^2 - on the surface, r=R
E=σ/ε_0=q/4πε_0R^2 - inside the shell, r<R
E=0
Field of an infinite wire and an infinite sheet
- infinite line, density lambda, cylindrical surface
E=λ/2πε_0 r - infinite plane sheet, density sigma, pillbox
E=σ/2ε_0
Electrostatic potential
- potential energy per unit charge
V=U/q - potential difference, work done per unit charge
V_2-V_1=dW/q - field is the negative gradient of potential
E=-dV/dx
Page 1 of 6. The full sheet, all 6 pages, opens free in the app.
What this Electrostatics sheet covers
- gauss's law
- gaussian surface
- Extending Gauss's law
- charged spherical shell
- Field of a uniformly charged spherical shell
- outside the shell, r>R
- on the surface, r=R
- inside the shell, r<R
- infinite straight charged wire
- infinite plane sheet
- Field of an infinite wire and an infinite sheet
- infinite line, density lambda, cylindrical surface
- infinite plane sheet, density sigma, pillbox
- electric potential
- potential difference
- Electrostatic potential
- potential energy per unit charge
- potential difference, work done per unit charge
- field is the negative gradient of potential
- Potential due to a point charge, and superposition
- potential energy
- system of charges
- Potential energy of a system of charges
- two charges, separated by r
- N point charges, sum over every pair
- single charge q sitting at potential V of an external field
- dipole potential
- potential due to a dipole
- Potential due to an electric dipole
- general point, angle theta from the dipole axis
- on the axis, theta=0 (towards +q)
- on the equator, theta=90 degrees
- dipole in a uniform field
- torque on a dipole
- Potential energy of a dipole in a uniform field
- equipotential surface
- Equipotential surfaces
- conductor
- electrostatic shielding
- Conductors under electrostatic conditions
- Polar vs nonpolar dielectrics
- Polar dielectrics
- Nonpolar dielectrics
- dielectric constant
- dielectric strength
- Polarisation reduces the net field
- capacitance
- parallel plate capacitor
- defining ratio
- parallel plates, area A, gap d
- unit, farad
- spherical capacitor
- cylindrical capacitor
- Capacitance of other shapes
- spherical, radii a and b
- cylindrical, length l, radii a and b
- n plates, alternately connected
- dielectric slab
- capacitance with dielectric
- Capacitance with a dielectric slab
- slab of thickness t < d, constant k
- slab fills the entire gap, t=d
- a conducting slab, k to infinity
- Capacitors in series vs parallel
- Series
- Parallel
- Two capacitors sharing charge
- joined plus to plus, common V
- energy lost as heat and spark
- energy stored in a capacitor
- charging it, three forms
- energy density in the field
- displacement current
- van de graaff generator
- 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.
More Physics Class 12 revision notes
- AC Circuits
- Current Electricity
- Dual Nature of Radiation and Matter
- Electromagnetic Induction
- Kinetic Theory of Gases and Radiation
- Magnetic Fields due to Electric Current
- Magnetic Materials
- Mechanical Properties of Fluids
- Oscillations
- Rotational Dynamics
- Semiconductor Devices
- Structure of Atoms and Nuclei
- Superposition of Waves
- Thermodynamics
- Wave Optics