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Physics · Electricity · Ohm's law
Ohm's law for a fixed resistor
Build a simple series circuit with an ammeter, a fixed resistor, and an adjustable supply. Read the voltmeter across the resistor and the ammeter in the line. Increase V step by step and tabulate I — R = V/I should come out constant.
supply voltage
V = 1.00 V · I = 0.100 A · R = 10.00 Ω
Results table
| V (V) | I (A) | R (Ω) |
|---|---|---|
| 1.0 | — | — |
| 2.0 | — | — |
| 3.0 | — | — |
| 4.0 | — | — |
| 5.0 | — | — |
| 6.0 | — | — |
Plot · V vs I
Exam-style questions
1. Ohm's law states that, for a metallic conductor at constant T:
2. On a graph of V (y-axis) vs I (x-axis) for a fixed resistor, the GRADIENT represents:
3. Why is the AMMETER in SERIES and the voltmeter in PARALLEL?
4. A resistor obeys Ohm's law from 0–5 V but at 6 V the V-I graph BENDS. Why?