• $summary_{type}$: revision
• $word_{count}$: 180

Essential formulas: c = 1/sqrt($mu_0$$epsilon_0$) = 3 x 10^8 m/s. $I_d$ = $epsilon_0$d$\frac{Phi_E}{dt}$. $E_0$/$B_0$ = c. u = $epsilon_0$$E^2$ = $B^2$/$mu_0$ ($u_E$ = $u_B$). I = $\frac{1}{2}$c$epsilon_0$$E_0^2$. S = $\frac{1}{mu_0}$(E x B). Pressure: I/c (absorb), 2I/c (reflect). v = $\frac{c}{n}$, n = sqrt($mu_r$$epsilon_r$). lambdaf = c.

JEE strategy by question type: (1) Displacement current: use $I_d$ = $epsilon_0$AdE/dt or equivalently $I_d$ = CdV/dt. (2) E-B relationship: $B_0$ = $\frac{E_0}{c}$ (B is always much smaller numerically in SI). (3) Direction: use E x B for propagation direction. (4) Intensity: I = $\frac{1}{2}$c$epsilon_0$$E_0^2$ — memorize this one formula and derive the rest. (5) Radiation pressure: remember the factor of 2 for reflection. (6) Spectrum questions: know the order, sources, and one key application per region. (7) Speed in medium: v = $\frac{c}{n}$ = $\frac{c}{sqrt}$($epsilon_r$) for non-magnetic materials. Common traps: confusing absorption and reflection pressure, forgetting that E and B are in phase (not 90 degrees out of phase), and mixing up $E_0$ with $E_{rms}$.