ECE 202 Test 1 Equation Sheet

Fundamental Equations:

v = [dw/dq]

i = [dq/dt]

p = [dw/dt] = vi = i²r = [(v²)/r]

Ohm's Law: v = ir

Kirchoff's Laws: KCL:åi_n = 0 (Sum of the currents entering and leaving a node is zero)

KVL:åV = 0 (Sum of the voltage drops around a closed loop equals zero)

Resistors is Series: R_eq = åR

Resistors in Parallel: [1/(R_eq)] = å[1/R] For just 2 resistors: R_eq = [(R₁+R₂)/(R₁R₂)]

Voltage Divider:

v₁ = [R1/(R1+R2)]v_s

Current Divider:

i₁ = [R2/(R1+R2)]i_s

Delta-Wye Conversion:

R₁ = [(R_bR_c)/(R_a+R_b+R_c)]

R₂ = [(R_aR_c)/(R_a+R_b+R_c)]

R₃ = [(R_aR_b)/(R_a+R_b+R_c)]

Wye-Delta Conversion:

R_a = [(R₁R₂+R₂R₃+R₃R₁)/(R₁)]

R_b = [(R₁R₂+R₂R₃+R₃R₁)/(R₂)]

R_c = [(R₁R₂+R₂R₃+R₃R₁)/(R₃)]