Circuit rules, potential dividers and internal resistance

Question 1

What is the current rule?

Answer 1

At any junction in a circuit, the total current leaving the junction is equal to the total current entering the junction.
(Current is split across parallel branches)

Question 2

What is the potential difference rule?

Answer 2

For two or more components in series, the total pd across all the components is equal to the sum of the potential differences across each component.
(Voltage across parallel branches is the same)

Question 3

How would you find the total resistance across R₁ and R₂ in series?

Answer 3

Rₜ = R₁ + R₂

Question 4

How would you find the total resistance across R₁ and R₂ in parallel?

Answer 4

1/Rₜ = 1/R₁ + 1/R₂

Question 5

What is the internal resistance?

Answer 5

The resistance of the battery / cell.

Question 6

On the graph V = ε - Ir, where can you find the internal resistance?

Answer 6

The negative gradient.

Question 7

On the graph V = ε - Ir, where can you find the emf?

Answer 7

The y-intercept.

Question 8

Give the potential divider equation

Answer 8

V₁/V₂ = R₁/R₂

Question 9

What does the potential divider equation show?

Answer 9

The ratio of the pds across each resistor is equal to the ratio of the resistances.