Topicm5ed2a2a18b0b20e4_1528449000663_0Topic

Determination of electrical resistanceresistanceresistance and powerpowerpower dissipated on a resistor supplied with battery. MeasurementmeasurementMeasurement uncertainty

Levelm5ed2a2a18b0b20e4_1528449084556_0Level

Second

Core curriculumm5ed2a2a18b0b20e4_1528449076687_0Core curriculum

VI. Electricity. The student:

16) experimentally:
e) determines the resistance of the conductor by measuring the voltage at its ends and the current flowing through it.

Timingm5ed2a2a18b0b20e4_1528449068082_0Timing

45 minutes

General learning objectivesm5ed2a2a18b0b20e4_1528449523725_0General learning objectives

Determination of the resistance of the conductor and the powerpowerpower dissipated on it.

Key competencesm5ed2a2a18b0b20e4_1528449552113_0Key competences

1. Connecting circuits according to the diagram.

2. Performing voltage and current measurements.

3. Determination of resistanceresistanceresistance and powerpowerpower as well as estimation of measurementmeasurementmeasurement uncertainties.

Operational (detailed) goalsm5ed2a2a18b0b20e4_1528450430307_0Operational (detailed) goals

The student:

- builds an electrical circuit according to the diagram,

- determines resistance and power and estimates measurement uncertainties.

Methodsm5ed2a2a18b0b20e4_1528449534267_0Methods

1. Formulating problems and ideas for solving them.

2. Organizing and using obtained results in new tasks of a practical or theoretical nature.

Forms of workm5ed2a2a18b0b20e4_1528449514617_0Forms of work

1. Experimenting in groups.

2. Work in groups over the obtained results.

Lesson stages

Introductionm5ed2a2a18b0b20e4_1528450127855_0Introduction

Answer the introductory questions for the lesson.

1. What is voltage and what kind of device do we use to measure it?
2. What is the current intensity and what kind of device do we use to measure it?
3. Define the electrical resistance.
4. How do we connect a ammeterammeterammeter in the electric circuit?
5. How do we connect a voltmetervoltmetervoltmeter in the electric circuit?

Procedurem5ed2a2a18b0b20e4_1528446435040_0Procedure

[Interactive graphics]

Experiment

Determination of the value of electrical resistanceresistanceresistance and dissipated powerpowerpower using an ammeterammeterammeter and a voltmetervoltmetervoltmeter.

Research hypothesis: 
Using an ammeter and a voltmeter, you can determine the resistor resistance and the power dissipated on it with acceptable accuracy.

1. Build the experimental circuit according to the diagram

[Illustration 1]

2. Measure the current in the circuit using an ammeter.
3. Measure the voltage on the resistor using a voltmeter.
4. Change the battery supplying the circuit to another one and repeat the measurements.
5. Write down the results in the measurementmeasurementmeasurement table.

[Table 1]

6. Repeat steps 1 to 5 for the circuit built according to the diagram below.

[Illustration 2]

7. Write down the results in the measurement table.

[Table 2]

Elaboration of results:

1. Based on the measurements made, determine for both measurement tables the resistanceresistanceresistance and the powerpowerpower dissipated on the resistor.

Comments:

- If the measurements were performed correctly, the results for the measurement table No. 1 and No. 2 differ.
- Differences arise from the fact that both an ammeter and a voltmeter are not ideal devices.
- The results of measurements are influenced by the internal resistance of the measuring instruments.m5ed2a2a18b0b20e4_1527752256679_0- If the measurements were performed correctly, the results for the measurement table No. 1 and No. 2 differ.
- Differences arise from the fact that both an ammeter and a voltmeter are not ideal devices.
- The results of measurements are influenced by the internal resistance of the measuring instruments.

3. Determine the lowest $R_{\min }$ and the largest $R_{\max }$ values of the resistance based on all measurements from both measurement table No. 1 and No. 2.

4. Determine the uncertainty of $R_{\mathrm{average}}$ from the formula $∆R_{\mathrm{average}}=\frac{1}{2}(R_{\max }-R_{\min }).$

5. Proceeding in the same way as in the case of resistance, determine the uncertainty of the average power $P_{average}$.

6. Write down correctly the resistanceresistanceresistance measurement result together with measurement uncertainty.

7. Write down correctly the powerpowerpower measurement result together with measurement uncertainty.

Lesson summarym5ed2a2a18b0b20e4_1528450119332_0Lesson summary

- To determine the electrical resistance and resistor power, you must build an electrical circuit consisting of: electrical wires, battery, resistor, ammeter and voltmeter.
- Then measure voltage and current.
- Based on the experimental results, you determine resistance and power.m5ed2a2a18b0b20e4_1527752263647_0- To determine the electrical resistance and resistor power, you must build an electrical circuit consisting of: electrical wires, battery, resistor, ammeter and voltmeter.
- Then measure voltage and current.
- Based on the experimental results, you determine resistance and power.

Selected words and expressions used in the lesson plan

ammeterammeterammeter

measurementmeasurementmeasurement

powerpowerpower

resistanceresistanceresistance

voltmetervoltmetervoltmeter