Lab work. Assembling an electric circuit and measuring current and voltage in its parts
The aim is to assemble a circuit and measure the current and voltage in different parts of it. Equipment: a school current source, an ammeter, a voltmeter, two lamps, a switch and connecting wires. The circuit is assembled one element after another with the switch open: source, switch, ammeter, both lamps; the voltmeter is connected in parallel to the lamp being measured. The source knob is set to 4 V and later to 6 V; the switch is closed and the readings are written in a table, then the voltmeter is moved to the second lamp. The scale division value is found by dividing the instrument’s limit by the number of divisions. The switch is always opened before instruments are reconnected. The work is done only under a teacher’s supervision with a low-voltage school source; lamps may become hot.
Prepare a table: columns — source voltage (4 V, 6 V), ammeter reading I, voltage U₁ across lamp 1, voltage U₂ across lamp 2. Work under the teacher’s supervision. Conclusion: does the ammeter reading change if you move it between the lamps? Compare U₁ + U₂ with the source voltage (the law for this is in lesson 21).