8 grade. Lab 4. Lesson

The title of the laboratory work: Study of the dependence of current on voltage in a section of a circuit

Purpose of the work: 

• Make sure that the current is directly proportional to the voltage in the section of the circuit.
• Analyze experimentally obtained data and record them taking into account errors.

Expected results:

• Electric current in directly proportional to the voltage in the section of the circuit. 

Teacher’s Guide:

• Divide the students to 3 students in each group.
• Before starting laboratory work, read the safety rules:

• To download the worksheet, please follow this link:

Theoretical part

Ohm’s law: electric current through a conductor between two points is directly proportional to the voltage across the two points.

Sources:

1. Электрическая цепь и ее составные части, сила тока, напряжение. (2018). Физика. Учебник для 8 класса общеобразовательной школы. 
2. Закон Ома для участка цепи. (2018). Физика. Учебник для 8 класса общеобразовательной школы

Experimental part

Experiment 1. Measuring electric current.

Procedure:

Step 1. Determine the ammeter and the voltmeter division value. Enter the result in the table.

Step 3. By moving the rheostat slider, take readings from the ammeter and voltmeter. Write down the voltage and current values in the table, taking into account the measurement error. Take the reading error to be equal to half the scale of the instrument.

Step 4. Using the obtained voltage and current values, construct a graph of current versus voltage, I(U). Draw the graph so that the line passes through or touches the range of measured values.

Step 5. Draw a conclusion.

Research part

№	Ammeter error ΔI, A	Electric current I, A	Current with error I±ΔI, A	Voltmeter error ΔU, A	Voltage U, В	Voltage with error U±ΔU, В
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2
3
4
5
6

When deriving conclusions, answer the following questions:

• Which dependency graph did you receive?
• Does the result of the experiment confirm Ohm’s law?

Conclusion

The current strength is directly proportional to the voltage across the circuit section. The experimental results confirm Ohm’s law.