random stuff i know i need to remember

electric dipole moment formula and direction

p = qs, where s is seperation

negative to positive

torque = pEsin(theta)

What is theta?

Angle between p and E

Electric field units

N/C

Torque/work unit

N-m or J

Energy unit

J

U_dipole = −pEcos(ϕ)

What is the theta thing?

angle between p and E

electric potential/voltage unit

V

V_cap = | E | x = (x/d) * ΔV_cap

What is x, what is d?

x is current distance value (THIS IS TRUE FOR SECOND FORMULA TOO)

d is final distance value at end of capacitor

V_{outside sphere} = (R/r) * V₀ where V₀ = K(Q/R)

What is big R?

Radius of sphere

V_dipole = Kpcos(θ)/r²

What is theta?

angle between p and point being measured

λ = Q/L

What is greek character, and units?

Linear charge density, C/m

σ = Q/A

What is greek character and units?

Surface charge density, C/m²

I = ρA_{cross section}v_drag

what is ρ?

density of fluid

R = ρL/A_{cross section}

What is ρ?

resistivity

Current unit

A

Resistivity unit

Ohm-m

Power unit

W

You’re converting 1 cm² to m². What do you do?

1.0 cm² = (1.0×10^-2m/1.0cm)*(1.0×10^-2m/1.0cm) = 1.0×10^-4m²

Another formula for current, relating to number of charged objects

I = q₊N₊/t diff - q_-N_-/t diff

Direction of magnetic dipole moment vector, and units

south pole to north pole, A-m^²

Magnetic field units

T

Right hand rule for forces

Thumb is F. Pointer is v or I. Middle is magnetic field.

frequency units

Hz

torque = |m||B|sinθ

U_mag = -|m||B|cosθ

What is θ?

Angle between vectors m and B

Kinematic eq missing Δx (the one used for practice exam 2 prob 8)

v_f = v₀ + at

Kinematic eq missing a

Δx = ((v_f + v₀)/2) * t

Kinematic eq missing v_f

Δx = v₀t + (1/2)at²

Kinematic eq missing t (the hard one)

v²_f = v²₀ + 2aΔx

Picture shows Biot-Savart for small piece of current as listed on the practice exam.

Definition is alternative equation I can use without the cross product:

Do currents moving in the same direction attract or repel?

Attract

What is L in the wave optics problems

Distance from slits to patterns

y diff = L*lambda/d for double slit interference

what is d, and what are the positions this measures

d is distance between slits

position difference of bright fringes

y_p = p*L*lambda/a for single slit diffraction

what is a, and what are the positions this measures

a is width of slit

y_p is distance of dark fringe from the central maximum

w = 2L*lambda/a for single slit diffraction

what is a, and what is w

a is width of slit

w is width of central maximum

w = 2.44L*lambda/D for circular aperture diffraction

what is D, and what is w

D is diameter of aperture (hole)

w is width/diameter of central maximum