1.resistors of 6 ohms and 18 ohms are connected in series to a 72 volt source find a) current through 6 ohm b)

Question

current through the 18 ohms, c) and the effective resistance.

2. solutions for a, b, and c with a parrallel connection.

Answer 1

Series:
Add up the restance.

Rt = (6 + 18) ohms

Rt = 24ohms

V = IR

V/R = I

a) I = 3 amps

Current at R1 = Current at R2 in series.

b) I = 3amps

c) Rt = 24 ohms


Parallel:

Voltage at R1 = voltage at R2

a) V/R = I

72/6 = 12amps at the 6ohm resistror

b)

72/18 = 4amps at the 18ohm resistor

c)

Rt = 1 / (1/R1) + (1/R2)

Rt = 1/ (1/6ohms) + (1/18ohms)

Rt = 1/ (2/9ohms)

Rt = 9/2 ohms

Rt = 4.5 ohms

Shortcut for two:

Rt = (R1 + R2) / (R1 x R2)

Answer 2

1.
a) current through 6 ohm = 72/(6 + 18) = 3 A
b) current through the 18 ohms =
72/(6 + 18) = 3 A
c) the effective resistance = 24Ω

2.
a) current through 6 ohm = 72 V/6 Ω = 12 A
b) current through the 18 ohms =
72/18 = 4 A
c) the effective resistance = 72 V/16 A = 4.5Ω