Measuring Current in Electrical Circuits – A Lab Exercise
Grade 9 ScienceName: ______
Obtain the electrical circuit kits and 1 ammeter then follow these steps carefully while answering related questions (*) as you proceed.
Step 1
Notice that some ammeters have different ranges of measurement:
Convert the following:
100 mA = / A / 0.05 A = / mA25 mA = / A / 0.300 A = / mA
A: Series Circuits
Step 2
Connect a circuit as shown in the diagram.
Use 2 cells, 1 lamp and 1 ammeter.
*Measure the amount of current at the positions shown.
A1 =A2 =
*How does the current compare between the above 2 positions? Can you suggest a reason for this result?
Step 3
Connect a circuit as shown in the diagram.
Use 2 cells, 2 lamps in series and 1 ammeter.
*Measure the amount of current at the positions shown.
A1 =A2 =
A3 =
*How does the current compare at the above 3 positions?
*How do the current readingsin step 3 compare to that in step 2? Suggest a reason for the difference.
*Suggest a rule or “law” regarding current in series circuits:
B: Parallel Circuits
Step 4
Connect a circuit as shown in the diagram.
Use 2 cells, 2 lamps in parallel and 1 ammeter.
*Measure the amount of current at the positions shown.
A1 =A2 =
A3 =
A4 =
*How does A1 compare to A4? ______
*How does A2 compare to A3? ______
*How does A1 compare to A2 and A3? ______
*Suggest a rule or “law” regarding current in the above circuit:
Step 5
Connect a circuit as shown in the diagram.
Use 2 cells, 3 lamps in parallel and 1 ammeter.
*Measure the amount of current at the positions shown.
A1 =A2 =
A3 =
A4 =
A5 =
*How does A1 compare to A5? ______
*How does A2, A3 and A4 compare to each other? ______
*How does A1 compare to A2, A3 and A4? ______
*Suggest a rule or “law” regarding current in parallel circuits:
The above “laws” are called “Kirchoff’s Current Laws”.
Complete the following phrases:
When electric loads are connected in series, the current measurements ______.
When electric loads are connected in parallel, the current measurements ______.
When finished, carefully put the equipment back in the kit containers.
Measuring Voltage in Electrical Circuits – A Lab Exercise
Grade 9 ScienceName: ______
Obtain the electrical circuit kits and 1 voltmeter then follow these steps carefully while answering related questions (*) as you proceed.
A: Parallel Circuits
Step 1
Connect a circuit as shown in the diagram.
Use 2 cells, 1 lamp and 1 voltmeter.
*Measure the voltage at the positions shown.
V1 =V2 =
*How does the voltage compare between the above 2 positions? Can you suggest a reason for this result?
Step 2
Connect a circuit as shown in the diagram.
Use 2 cells, 2 lampsin parallel and 1 voltmeter.
*Measure the voltage at the positions shown.
V1 =V2 =
V3 =
*How does the voltage compare at the above 3 positions?
*How do the voltage readingsat the lamps in step 2 compare to that in step 1?
*Suggest a rule or “law” regarding voltage in parallel circuits:
B: Series Circuits
Step 3
Connect a circuit as shown in the diagram.
Use 2 cells, 2 lamps in series and 1 voltmeter.
*Measure the voltage at the positions shown.
V1 =V2 =
V3 =
*How does V2 compare to V3?
*How does V1 compare to V2 and V3?
*Suggest a rule or “law” regarding voltage in the above circuit:
Step 4
Connect a circuit as shown in the diagram.
Use 2 cells, 3 lamps in seriesand 1 voltmeter.
*Measure the voltage at the positions shown.
V1 =V2 =
V3 =
V4 =
*How does V2 compare to V3 and V4? ______
*How does V1 compare to V2, V3, and V4?
______
*Suggest a rule or “law” regarding voltage in the above circuit:
The above “laws” are called “Kirchoff’s Voltage Laws”.
Complete the following phrases:
When electric loads are connected in series, the voltage measurements ______.
When electric loads are connected in parallel, the voltage measurements ______.
When finished, carefully put the equipment back in the kit containers.