Formula, constant sheet for Test II, PHY2061
µ0 = 4 10-7 Tm/A
(Energy from B-field)/volume = B2/(2µ0) =
Blong wire=µ0i/2d ; Bmoving charge=qv x r/|r|3; Bideal solenoid=µ0ni
Bon axis of circ. loop=µ0iR2/(2(R2+z2)3/2); BToroid=µ0iN/2r
ξ = -d φB/dt (Lenz’ law)
Force between two current carrying wires, L long, d apart:
F21=µ0Li1i2/2d
Ampere’s Law:  Bds = µ0ienclosed by loop (both B and ds are vectors, the
integral is around the loop)
q=CV; charging a capacitor in an RC circuit q=Cξ(1-exp(-t/RC))
i=(ξ/R)exp(-t/RC) where ‘ξ’ is the emf and q is the charged stored
on the capacitor
discharging a capacitor: q=q0 exp(-t/RC) ; i= -(ξ/R)exp(-t/RC)
Hall effect voltage: ∆VH = iB/net where n is the density of charge
carriers (#/Volume), e=1.602 10-19 Coulomb, t=thickness of strip of
conductor, B is the component of the field perpendicular to the charge
carrier flow
Transformer: ∆Vp/Np = ∆Vs/Ns
Magnetic flux: φB = B  A , where this is a dot product between two
vectors
L/l = inductance/length = µ0n2A, where n is the turns/meter and A is the
area
Energy stored in an inductance L carrying a current i: ½ L i2
In an ac LRC circuit, XC=1/C ; XL=L ;
total impedance Z=(R2+(XL-XC)2)1/2; ‘resonance’ is when the impedance
is at a minimum, i. e. when XL=XC.
tan Ф = (XL-XC)/R