Formulas 2

Faraday's Law

 
  • Faraday's law:
Induced emf = -ΔΦB/∆t (through a fixed area)
  • Magnetic flux:
ΔΦB = B ΔA cosθ
  • Induced current:
I = emf/R
  • Transformer:
V2/N2 = V1/N1,    V2 I2  ≤  V1 I1

Electromagnetic Waves

 

  • Sinusoidal waves:
E(x,t) = Emaxsin(kx - ωt + φ),  Brad = Erad/c
  • Energy flux S, intensity I:  
S = (1/0)E B,  I is proportional to Emax2
  • Polarizers:
Itransmitted = I0cos2θ.

Geometrical Optics

 
  • Law of reflection:
θ1 = θ2
  • Law of refraction:
n1sinθ1 = n2sinθ2
  • Total internal reflection:
sinθc = n2/n1
  • Mirror equation:
1/xo + 1/xi = 1/f,  M = -xi/xof = R/2
  • Lens equation:
1/xo + 1/xi = 1/f,  M =- xi/xo