IB Physics 5.3: Internal Resistance

What is internal resistance in a circuit?

• The total resistance in a circuit

• Opposition to the flow of current within a power source

• The voltage drop across a resistor

• The ability of a circuit to conduct electricity

How is internal resistance represented in a circuit diagram?

• The symbol 'IR'

• Big, uppercase letter 'R'

• The word 'resistance' spelled out

• Small, lowercase letter 'r'

What is the formula to calculate the total resistance in a circuit with internal resistance?

• R = R0 - r

• R = R0 * r

• R = R0 / r

• R = r + R0

Explain the effect of increasing internal resistance on the current in a circuit.

• Has no effect

• Decreases

• Increases

• Remains constant

Discuss the factors that affect the internal resistance of a cell or battery.

• Number of electrons in the circuit

• Color of the cell

• Type of electrolyte, temperature, surface area of electrodes, distance between electrodes

• Brand of the battery

Compare and contrast the concepts of internal resistance and external resistance in a circuit.

• Internal resistance is measured in ohms, while external resistance is measured in amperes.

• Internal resistance is related to temperature, while external resistance is related to voltage.

• Internal resistance is within the power source, while external resistance is in the rest of the circuit components.

• Internal resistance is constant, while external resistance varies with the type of circuit.

How does internal resistance affect the terminal potential difference of a cell?

• Internal resistance reduces the terminal potential difference of a cell.

• Internal resistance causes the terminal potential difference of a cell to fluctuate.

• Internal resistance has no effect on the terminal potential difference of a cell.

• Internal resistance increases the terminal potential difference of a cell.

Explain the concept of EMF and its relationship with internal resistance.

• EMF is related to internal resistance as it is the maximum potential difference when no current is flowing, and the actual terminal voltage is reduced when current flows due to the presence of internal resistance.

• EMF decreases as internal resistance increases

• EMF is unrelated to internal resistance and has no effect on the terminal voltage

• Internal resistance is the maximum potential difference when no current is flowing

Discuss the practical applications of understanding internal resistance in real-life scenarios.

• Internal resistance only affects theoretical calculations and has no real-world impact

• Understanding internal resistance has no practical applications in real-life scenarios

• Understanding internal resistance can help in designing efficient electrical circuits and batteries, optimizing power transmission, and improving the performance of electronic devices.

• The concept of internal resistance is too complex to be applied in practical situations

Solve the following problem: A cell has an EMF of 1.5V and an internal resistance of 0.3 ohms. If the external resistance is 2 ohms, calculate the current flowing through the circuit.

• 1.5A

• 0.5A

• 3A

• 0.2A