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What does the AC Circuits revision sheet cover?

AC source, Instantaneous current, RMS value, average value, Average and RMS value, said precisely, phasor, Phasors, AC through R, L, C alone, Resistor, Inductor, Capacitor, impedance.

Is this for Class 12 Maharashtra HSC Physics?

Yes, it is written for the Maharashtra HSC Physics syllabus.

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AC Circuits — Class 12 Maharashtra HSC Physics revision notes

A 5-page visual revision sheet for AC Circuits, 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.

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AC Circuits in one look

the source keeps flipping, and every element answers it differently

AC source: emf reverses direction every half cycle
Instantaneous current: generally out of step with e by phase phi
RMS value: the steady DC that delivers the same average heating

Average and RMS value, said precisely

average of sinω t over a full cycle is zero, halves cancel exactly
mean AC is instead defined over half a cycle
average over half a cycle: i_av = 0.637 i_0 = 2/pii_0, likewise e_av=0.637 e_0
RMS squares first, always positive, averages that, then square-roots
i_rms = i_0/√2 = 0.707 i_0, e_rms = e_0/√2
power, heating and moving-coil readings always use RMS values, never peak

Phasors

a phasor is a rotating vector, length e_0 or i_0, spinning anticlockwise at speed omega
its vertical projection at any instant gives the instantaneous value, i_0sinω t
two phasors with angle phi between them carry that same phase difference
phase and amplitude questions then become ordinary vector addition of phasors

Page 1 of 5. The full sheet, all 5 pages, opens free in the app.

What this AC Circuits sheet covers

AC source
Instantaneous current
RMS value
average value
Average and RMS value, said precisely
phasor
Phasors
AC through R, L, C alone
Resistor
Inductor
Capacitor
impedance
lcr circuit
Impedance of a series LCR circuit
voltage across each element, same current i throughout
e_L and e_C are 180 degrees out of phase, so they subtract
dividing through by i_0 gives the impedance
phase angle by which emf leads current
Impedance, the special forms
power factor
wattless current
Power in an AC circuit
average power over a full cycle
power factor, from the impedance triangle
pure R, non-inductive circuit, X_L=X_C
pure L or pure C alone
lc oscillations
Series vs parallel resonance
Series vs parallel resonant circuit
Series (acceptor)
Parallel (rejector)
q factor
quality factor
bandwidth
Sharpness of resonance, the Q factor
half-power points, symmetric about the resonant angular frequency
bandwidth, current falls to 1/√2 of peak at its edges
choke coil
Symbols
Traps that cost marks
Tricks that save time

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