Electricity
Circuit bench
Predict the current, then close the switch and read the meters.
I = V / R
Apparatus
- Cell
- Two resistors
- Ammeter in series
- Voltmeter across the resistors
Method
- Set the cell voltage and the two resistances.
- Choose single, series, or parallel, and predict the ammeter reading.
- Close the switch and compare.
- Swap series for parallel without changing the resistors. The current should jump.
This is a low-voltage model. Do not rebuild it from the mains.
Ammeter
open
R equivalent
9Ω
V on R1
—V
V on R2
—V
Arrangement
The ammeter stays blank until the switch is closed.
Series: one current, voltages that add. Parallel: full voltage on each branch, currents that add.
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