Electromagnetic Waves and Communication System — Class 11 Maharashtra HSC Physics revision notes
A 5-page visual revision sheet for Electromagnetic Waves and Communication System, 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
Electromagnetic Waves and Communication System in one look
the spectrum, propagation, and the elements of a communication link
What an EM wave is
- Maxwell's equations link E and B: Gauss's laws for E and for B
- Faraday: a changing B induces an emf; Ampere-Maxwell: a current or changing E makes B
- charge at rest: only a steady E; steady speed: a steady B too; still no wave
- an accelerated charge radiates: oscillating E makes oscillating B, which regenerates E
- the wave has the frequency of the charge's oscillation; its energy comes from the source
Characteristics of EM waves
- needs no medium: it crosses vacuum
- E, B and the propagation direction are mutually perpendicular, so EM waves are transverse
- E and B oscillate in phase: they peak together
- obey superposition; carry no charge, so E and B fields don't deflect them
Speed and the E-B ratio
- speed in free space
c = frac1√μ_0ε_0 = 3×10^8 m s^-1 - speed in a medium
v_m = frac1√με - ratio of amplitudes
E_0/B_0 = c - intensity
I ∝ E_0^2 ∝ B_0^2 - frequency and wavelength
c = fλ
Page 1 of 5. The full sheet, all 5 pages, opens free in the app.
What this Electromagnetic Waves and Communication System sheet covers
- electromagnetic wave
- What an EM wave is
- Characteristics of EM waves
- Speed and the E-B ratio
- speed in free space
- speed in a medium
- ratio of amplitudes
- intensity
- frequency and wavelength
- Speed and intensity: the limits
- electromagnetic spectrum
- The EM spectrum, in order of increasing frequency
- Reading the spectrum
- ground wave
- sky wave
- space wave
- Propagation of radio waves
- Range of a space wave
- range from a transmitter of height h
- total range, transmitter height h_t, receiver height h_r
- communication system
- transducer
- Elements of a communication system
- modulation
- carrier wave
- Types of modulation
- Amplitude (AM)
- Frequency (FM)
- Phase (PM)
- 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 Waves and Communication System 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.