physics II midterm 2 equations

steady charge = density x area of cross section

current density = 1/resistance x electric field

power = current x potential

power absorbed/emitted by emf = current/work on unit charge required to maintain potential difference

and which one to use when

power at which energy is transformed into thermal energy

V²/R: when voltage is constant

I²R: when current is constant?

series circuit

SCAV (same current, add voltage)

R_eq = R₁+ R₂ ….

parallel circuit

SVAC (same voltage, add current)

R_eq = (1/R₁ +1/R₂ …)^-1

series capacitors

SQAV (same charge, add voltage)

C_eq = (1/C₁ + 1/C₂ + …)^-1

parallel capacitors

SVAQ (same voltage, add charge)

C_eq = C₁ + C₂ +….

force of magnetic field = q (V x B)

direction: sweep hands from place of velocity to magnetic field), thumb points direction of force

F_c = F_B = (mv²)/r

force of magnetic field in uniform circular motion

radius of circular motion

frequency = 1/period

p = V_//T

pitch of helix is parallel velocity (to B) x period

direction?

magnetic field of coil

right hand rule → curl around current, thumb is magnetic field

magnetic dipole moment

magnetic field of magnetic dipole

magnetic field of a solenoid

n = number of turns

potential energy of magnetic dipole

torque on a coil due to magnetic dipole

force of magnetic field on an angled wire

θ = angle between B and L

force of single charge carrier in a wire perpendicular to magnetic field

number of charges in the wire of length L in wire perpendicular to magnetic field

net force of wire perpendicular to magnetic field