2.2 - Series and Parallel Circuits

Question 1

What does a series circuit look like?

Answer 1

Lots of components directly connected together in a single line [Diagram TBC]

Question 2

What does a parallel circuit look like

Answer 2

Components connected in several “branches” or “loops” [Diagram TBC]

Question 3

For components connected in SERIES, total current is…

Answer 3

… the same through every component

Question 4

For components connected in SERIES, total potential difference is…

Answer 4

… shared between all components

Question 5

For components connected in SERIES, total resistance is…

Answer 5

… the sum of the resistance of each component

Question 6

For components connected in PARALLEL, total potential difference is…

Answer 6

… the same for each component

Question 7

For components connected in PARALLEL, total current is…

Answer 7

… the sum of the current passing through each component

Question 8

For components connected in PARALLEL, total resistance is…

Answer 8

… less than the resistance of the smallest resistor

Question 9

Why does total resistance increase if a resistor is added in series?

Answer 9

• Adding a component decreases the potential difference for every component
  
  • because P.D is shared between components in series
• Decreasing the P.D. means current for every component must also decrease (V=IR)
• If current passing through each component decreases, total current also decreases
  
  • because current is the same between components in series
• Total resistance must increase if total current decreases (V=IR)

Question 10

Why does total resistance decrease if a resistor is added in parallel?

Answer 10

• Potential Difference is unchanged by adding a resistor
• Current through the old resistors is the same as before (V = I R, with V and R unchanged)
• New resistor must also have some current (V = IR)
• Total current is greater than before (old current + new current)
• Total Resistance must be smaller than before (V = I R, with V unchanchanged)

Question 11

How can you measure the current flowing through a component?

Answer 11

• Create a circuit with the component
  
  • unbroken circuit
  • has a power source
• Use an ammeter
  
  • In series (current is the same for components in series)

Question 12

How can you measure the potential difference across a component?

Answer 12

• Create a circuit with the component
  
  • unbroken circuit
  • has a power source
• Use a voltmeter
  
  • In parallel (potential difference is the same for components in parallel)

Question 13

How can you measure the resistance of a component?

Answer 13

• Create a circuit with the component
  
  • unbroken circuit
  • has a power source
• Measure the current passing through the component
  
  • Ammeter
  • In series (current is the same for components in series)
• Measure the potential difference passing through the component
  
  • Voltmeter
  • In parallel (potential difference is the same for components in parallel)
• Resistance is the potential difference divided by the current (V = I R )