1. The problem statement, all variables and given/known data There are 5 identical bulbs. All are glowing. Rank from brightest to dimmest. Some may be equal. 2. Relevant equations I= (ΔV)/R Req = [(1/R1)+ (1/R2) +...]^-1 (Parallel resistors; same delta V) Req = R1 + R2 + .... ( Series resistors; same current I) 3. The attempt at a solution Let all the bulbs have resistance R. A. Combine bulbs R and S ( parallel, same ΔV) Req = [(1/R)+(1/R)]^-1 = R/2 B. Combine R&S with P and T ( series, same I ) Req = (R/2) + R + R = 2.5 R C. Combine (R&S, P, T) with Q ( Parallel, same ΔV) Req = [(1/R)+(1/2.5R)]^-1 = 0.71R ΔV = ε- - > I = ε/Req = 1.4ε/R Now decompose to find individual currents: A. R(Q) = R; ΔV = ε --> I(Q) = ε/R R(R&S, P, T) = 2.5R --> I (R&S, P, T) = 0.4ε/R I (P) = I (T) = 0.4ε/R R(R&S)= R/2 ΔV (R&S) =( 0.4ε/R)*(R/2)= 0.2 ε ΔV (R) = ΔV (S) = 0.2ε R (S) = R (R) = R I (S) = I ( R) = 0.2ε/R ⇒Q >P=T >S =R This is incorrect t and I'd like to know what I did wrong. thanks in advance for any help.