Electromagnetic Induction — Class 12 Maharashtra HSC Physics revision notes
A 6-page visual revision sheet for Electromagnetic Induction, 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.
What this Electromagnetic Induction sheet covers
- Flux
- Changing flux
- Induced emf
- faraday's law
- Faraday's laws of electromagnetic induction
- Reading Lenz's law off a moving magnet
- motional emf
- Motional emf, a rod sliding on rails
- rod of length l sliding at speed v, field B perpendicular to the plane
- as a magnetic force on the free charges in the rod
- work per unit charge carried the length l
- current if the circuit has resistance R
- Motional emf in a rotating rod
- emf induced across a short segment dr at radius r
- integrated over the whole rod of length l, pivoted at one end
- in terms of frequency of rotation n
- generator
- ac generator
- AC generator, from Faraday's law
- flux through a coil of N turns rotating at angular speed omega
- peak emf
- so the output is
- back emf
- Back emf and back torque
- eddy current
- Induction and energy transfer
- flux through a loop of width L partly inside a field, as x shrinks
- induced emf and current
- force needed to pull the loop out at constant v
- rate of doing mechanical work equals the rate of heat production
- Eddy currents
- self-inductance
- self inductance
- Inductance of standard shapes
- long solenoid, n turns per unit length, length l, area A
- toroid of major radius R, minor radius r much less than R, N turns
- coaxial cable, inner radius a, outer radius b, length l
- series combination
- parallel combination
- Energy stored in a magnetic field
- work done building current i_0 against the back emf
- this work is stored as magnetic energy
- energy density inside a long solenoid
- mutual inductance
- Coefficient of coupling
- mutual inductance in terms of the two self-inductances
- K is the fraction of flux from one coil reaching the other
- perfectly coupled coils, K = 1
- a coil coupled to itself, L_1 = L_2 = L
- transformer
- The transformer
- primary and secondary emf, same flux per turn phi linked with both
- turns ratio equals voltage ratio
- ideal transformer, power in equals power out
- so current ratio is the inverse of the voltage ratio
- 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 Electromagnetic Induction 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
- Electrostatics
- 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