Three 45 Ω light bulbs and three 65 Ω light bulbs are connected in series. (a) What is the total resistance of the circuit? (b) What is the total resistance if all six are wired in parallel?

(a) 330 ohm in series

(b) 8.866 ohm in parallel

Explanation:

series resistance is the sum of all individual resistance.

R=R1+R2+R3 + ... + Rn

R=3*45+3*65=330 ohm

now for parallel use relation

1/R=1/R1 + 1/R2 + 1/R3 + 1/Rn

1/R=1/45 + 1/45 + 1/45 + 1/65 + 1/65 1/65

R = 8.866 ohm