Wyznaczanie oporu elektrycznego i mocy wydzielanej w oporniku zasilanym przez baterię. Niepewności pomiarów

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?

Experiment

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

Research hypothesis

• Using an ammeterammeterammeter and a voltmetervoltmetervoltmeter, you can determine the resistor resistanceresistanceresistance and the powerpowerpower dissipated on it with acceptable accuracy.

Instruction

1. Build the experimental circuit according to the diagram:

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Ilustracja przedstawia schemat obwodu elektrycznego. Na obrysie prostokąta, na górnym boku po lewej stronie kółko z literą A, na prawym boku kółko z dwoma odcinkami prostopadłymi wewnątrz, na lewym boku źródło zasilania (od dołu krótka kreska pozioma opisana minus, puste miejsce, dłuższa kreska pozioma opisana plus). Po prawej stronie na górnym i dolnym boku punkty, między nimi linia pionowa łączą je, na niej kółko z V.

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.

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

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Ilustracja przedstawia schemat obwodu elektrycznego. Na obrysie prostokąta, na górnym boku po prawej stronie kółko z literą A, na prawym boku kółko z dwoma odcinkami prostopadłymi wewnątrz, na lewym boku źródło zasilania (od dołu krótka kreska pozioma opisana minus, puste miejsce, dłuższa kreska pozioma opisana plus). Po lewej stronie na górnym i dolnym boku punkty, między nimi linia pionowa łączą je, na niej kółko z V.

7. Write down the results in the measurementmeasurementmeasurement table.

Elaboration of results

1. Based on the measurements made, determine for both measurementmeasurementmeasurement 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 ammeterammeterammeter and a voltmetervoltmetervoltmeter are not ideal devices.

• The results of measurements are influenced by the internal resistance of the measuring instruments.

2. Determine the average value of the resistanceresistanceresistance $R_{\mathrm{average}}$ and the power $P_{\mathrm{average}}$ dissipated on it on the basis of all measurements both from the measurementmeasurementmeasurement table No. 1 and No. 2.

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 powerpowerpower $P_{\mathrm{average}}$.

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

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

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 resistanceresistanceresistance and powerpowerpower.

Exercises

Glossary

Keywords

ammeterammeterammeter

measurementmeasurementmeasurement

voltmetervoltmetervoltmeter