Revise: Electromagnetic Induction, Generation and Distribution of Electricity
Alternating current, Faraday's and Lenz's laws, and how electricity is transmitted, wired into houses, and used safely.
Phi = BAcos(theta) — magnetic flux.
B=0.5T,A=0.02m^2,perpendicular → Phi=0.01Wb.
epsilon = -N(DeltaPhi/Deltat). Induced current opposes the change.
N=100, DeltaPhi=0.02Wb, Deltat=0.5s → epsilon=4V.
Vs/Vp = Ns/Np — transformer equation.
Np=1000,Ns=100,Vp=240V → Vs=24V.
P_loss = I^2 R — high voltage means low current, less loss.
10000V vs 1000V: 100x less power lost.
I_total = sum of individual appliance currents (parallel wiring).
2A+5A+3A = 10A on a 10A fuse.
I = V/R — wet skin has far lower resistance.
230V, wet skin (1000 ohms) → 230mA, dangerous.
Mains ratings quote RMS voltage, not peak.
A "230V" outlet actually swings +-325V.
Induction happens when flux CHANGES, not just when present.
A metal detector senses changes in flux.
The physics behind every electric generator.
A bicycle dynamo lights a lamp by spinning a magnet.
A transformer changes voltage, never total power.
A phone charger uses a step-down transformer.
It is current, not voltage, that determines heat loss.
Tall towers carry power at very high voltage.
Appliances are wired in parallel, not series.
Too many appliances at once can trip a breaker.
Danger depends on current, not voltage alone.
GFCI outlets exist because of this exact relationship.