3.2 - Electrical Circuits

Question 1

How do you find current and potential difference in a series circuit

Answer 1

• total current is same at any point on circuit
  I = I1 = I2
• total potential difference is split up across each component
  V = V1 = V2

Question 2

How do you find the total resistance in a series circuit

Answer 2

R = R1 + R2 + R3

Question 3

How do you find the total current and potential difference in a parallel circuit

Answer 3

• total current is equal to sum of currents through each resistor
  I = I1 + I2 + I3
• total potential difference is equal to p.d across each resistor
  V = V1 = V2H

Question 4

How do you find the total resistance in parallel

Answer 4

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

Question 5

Why does current increase in parallel but decrease in series

Answer 5

• more branches in parallel decreases resistance, therefore current increases as there are more pathways for electrons to flow
• more components in series increases resistance, therefore current decreases

Question 6

Why are ammeters attached in series but voltmeters are attached in parallel

Answer 6

• ammeters have a very low resistance
• voltmeters have a very high resistance so only allows a small amount of current through it