202 Series and parallel circuits

Series and parallel circuits end of lesson quiz

Here are a series of questions relating to series and parallel circuits. The questions will get gradually harder. The answers for all questions are at the bottom of the page for you to check against

Question 1.

Calculate the following:

a) total circuit resistance

b) circuit current

c) voltage dropped in the parallel

d) voltage dropped at the 1.4 ohm resistor

e) current in each leg of the parallel

Question 2.

Calculate the following:

a) total circuit resistance

b) circuit current

c) voltage dropped in the parallel

d) voltage dropped at the 3.5 ohm resistor

e) current in each leg of the parallel

Question 3.

Calculate the following:

a) current at 3 ohm resistor

b) ohm value of unknown resistor

c) total circuit resistance

d) total circuit current

e) total circuit voltage

f) voltage dropped at the 4.5 ohm resistor

Question 4.

Calculate the following:

a) resistance of the parallel

b) total circuit resistance

c) resistance of R1

d) voltage dropped at R1

e) voltage in the parallel

f) current in each leg of the parallel

Question 5.

Calculate the following:

a) voltage in the parallel

b) current at the 5 ohm resistor

c) current at R1

d) resistance of the parallel

e) total circuit resistance

Scroll down for answer and workings out for all questions

Question 1 answers

a) Rp = 1 / 9 + 1 / 6 = 1 / ans = 3.6 Ω

b) to calculate the circuit current you need the total resistance

Rt = 1.4 + 3.6 = 5 Ω

I = 50 / 5 = 10 A

c) V@Rp = I x 3.6 = 10 x 3.6 V

d) V@1.4 = 10 x 1.4 = 14 V

e) I@9 = 36 / 9 = 4 A

I@6 = 36 / 6 = 6 A

Question 2 answers

a) You will need to calculate the resistance in the parallel first

Rp = 1 / 8 + 1 / 7 + 1 / 4 = 1 / ans = 1.93 Ω

Rt = 3.5 + 1.93 = 5.43 Ω

b) I = 20 / 5.43 = 3.68 A

c) Vd@Rp = 3.68 x 1.93 = 7.1 V

d) Vd@3.5 = 3.68 x 3.5 = 12.88 V

e) I@8 = 7.1 / 8 = 0.89 A

I@7 = 7.1 / 7 = 1.01 A

I@4 = 7.1 / 4 = 1.78 A

Question 3 answers

a) I@3 = 10 / 3 = 3.33 A

b) R1 = 10 / 2.5 = 4 Ω

c) You will need to calculate the resistance in the parallel first

Rp = 1 / 3 + 1 / 4 = 1 / ans = 1.71 Ω

Rt = 4.5 + 1.71 = 6.21 Ω

d) I = 3.33 + 2.5 = 5.83 A

e) V = 6.21 x 5.83 = 36.2 V

f) Vd@4.5 = 4.5 x 5.8 = 26.2 V

Question 4 answers

a) Rp = 1 / 15 + 1 / 5 = 1 / ans = 3.75 Ω

b) Rt = 6 / 1 = 6 Ω

c) R@R1 = 6 – 3.75 = 2.25 Ω

d) Vd@R1 = 1 x 2.25 = 2.25 V

e) Vd@Rp = 6 – 2.25 = 3.75 V

f) I@15 = 3.75 / 15 = 0.25 A

I@5 = 3.75 / 5 = 0.75 A

Question 5 answers

a) V@20 = 20 x 0.5 = 10 V

b) There was a 10 V volt drop in the parallel so subtract this from the circuit voltage first

I@5 = 20 / 5 = 4 A

c) There is 0.5 A in one leg of the parallel, subtract this from the circuit current to give current in the bottom leg of the parallel

R@R1 = 10 / 3.5 = 2.86

d) Rp = 1 / 20 + 1 / 2.86 = 1 / ans = 2.5 Ω

e) Rt = 5 + 2.5 = 7.5 Ω