5.4 Electromotive force and internal resistance

• The terminal potential difference is less than the EMF due to internal resistance.


  True
• The formula relating EMF, terminal potential difference, and internal resistance is V = ε - Ir
• Arrange the following sources in order of increasing internal resistance:

  1️⃣ Lead-Acid Battery

  2️⃣ Alkaline Battery

  3️⃣ Lithium Battery
• In a simple electrical circuit, electrons flow from the positive terminal to the negative terminal of the battery.

  False
• The relationship between voltage, current, and resistance is defined by Ohm's Law.
• Match the term with its definition:

  EMF (ε) ↔️ Potential difference with no current flow

  Terminal Potential Difference (V) ↔️ Actual voltage available with current flow

  Internal Resistance (r) ↔️ Resistance within the source
• Temperature affects the internal resistance of a source.


  True
• Internal resistance reduces the terminal potential difference according to the formula V = $\epsilon - Ir$.
• The formula to calculate the current in a circuit with internal resistance is I = $\epsilon / (R + r)$.
• A battery with an EMF of 12 V and internal resistance of 0.5 Ω supplies a current of 2 A. The terminal potential difference is 11 V.
• The terminal potential difference is 11 V
• The relationship between EMF, terminal PD, and internal resistance is given by the formula $V =$$\epsilon - Ir$, where $I$ is the current
• The formula relating EMF, terminal PD, and internal resistance is $V =$$\epsilon - Ir$, where $\epsilon$ is the EMF
• What is the typical internal resistance of an alkaline battery?

  $0.1 \Omega$
• Describe the flow of electrons in a simple electrical circuit when closed:

  1️⃣ Electrons flow from the negative terminal of the battery

  2️⃣ Electrons move through the wires

  3️⃣ Electrons pass through the load

  4️⃣ Electrons return to the positive terminal of the battery
• A battery with an EMF of $12 V$ and internal resistance of $0.5 \Omega$ is connected to a $5.5 \Omega$ resistor. What is the current flowing through the circuit?


  $2 A$
• The formula to calculate the terminal potential difference is V = \epsilon - Ir</latex>
• The terminal potential difference is always less than the EMF due to the voltage drop across the internal resistance.
• A higher internal resistance or a larger current flow will result in a lower terminal potential difference.

  True
• The age of a battery typically increases its internal resistance due to corrosion and wear.

  True
• What does the symbol 'r' represent in the context of EMF and internal resistance?

  Internal resistance
• The electromotive force (EMF) represents the maximum potential difference when no current is flowing.
• Internal resistance within a source causes a voltage drop when current flows.
• Internal resistance reduces the terminal potential difference according to the formula $V =$$\epsilon - Ir$


  True
• What law defines the relationship between voltage, current, and resistance in a circuit?

  Ohm's Law
• The terminal potential difference is always equal to the EMF when internal resistance is present.

  False
• The terminal potential difference (PD) is equal to the EMF when no current is flowing.

  False
• The formula for terminal potential difference (PD) is V = \epsilon - Ir</latex>

  True
• In an example with an EMF of $12 V$, internal resistance of $0.5 \Omega$, and a current of 2 A</latex>, the terminal PD is 11 V
• The internal resistance of a source usually decreases with age due to corrosion.

  False
• Temperature fluctuations can affect the internal resistance of a source and need to be considered in experiments.

  True
• What does EMF represent in a circuit?

  Potential difference with no current flow
• What is the effect of internal resistance on the terminal potential difference?

  It reduces the terminal PD
• Why does internal resistance cause a voltage drop within a source?

  When current flows
• What is the function of a battery in a simple electrical circuit?

  Provides potential difference
• What does Electromotive Force (EMF) represent when no current is flowing?

  Maximum possible voltage
• The formula relating EMF, terminal potential difference, and internal resistance is V = $\epsilon - Ir$.
• Arrange the factors affecting internal resistance in order of importance:

  1️⃣ Material and construction

  2️⃣ Age of the source

  3️⃣ Temperature
• A simple electrical circuit must include a battery, wires, and a load.


  True
• What is the current flowing in a circuit with an EMF of 12 V, external resistance of 5.5 Ω, and internal resistance of 0.5 Ω?

  2 A