A-LEVEL Physics: 5.4.2: Required Practical: Investigating EMF & Internal Resistance (SaveMyExams)

Question 1

What is the Aim of the Required Practical ‘Investigating EMF & Internal Resistance’?

Answer 1

The Aim is to Investigate the Relationship Between the EMF & Internal Resistance, by Measuring the Variation of Current & Voltage, Using a Variable Resistor.

Question 2

What are the Variables in the Required Practical ‘Investigating EMF & Internal Resistance’? (5)

Answer 2

-Independent Variable: Resistance, R (Ω)

-Dependent Variables:
-Voltage (V)
-Current (A)

-Control Variables:
-EMF of the Cell (V)
-Internal Resistance of the Cell (Ω)

Question 3

What is the Method of the Required Practical ‘Investigating EMF & Internal Resistance’? (4)

Answer 3

-Connect the Cell & Resistor (Labelled r) in Series. Consider this as a Single Cell.

-With the Switch Open, Record the Reading on the Voltmeter.

-Set the Variable Resistor to its Maximum Value, Close the Switch, & Record V & the Reading of Current on the Ammeter. Make sure to Open the Switch Between Readings.

-Vary the Resistance on the Variable Resistor ~10 times.

Question 4

What are the Random Errors in the Required Practical ‘Investigating EMF & Internal Resistance’? (3)

Answer 4

-Do Not Use Worn-Out Cells.

-Do Not Take Fluctuating Readings from the Ammeter / Voltmeter; Wait Until it Stabilises.

-Take Repeat Readings & Calculate the Average to Reduce the Negative Effect of Anomalous Results.