Key relationship
R=V/I; ρ=RA/L; A=πd²/4.
Physics · Practical apparatus
Wire resistivity VI graph
Read voltage and current at several low-current settings and obtain resistance from the VI slope. Diameter measured with a screw gauge determines area; correct the ammeter zero.
Open the interactive experiment →Wire resistivity VI graph
V/I மூலம் மின்தடை பெறவும். கம்பி பரப்பையும் நீளத்தையும் கொண்டு ρ=RA/L. அம்மீட்டர் பூஜ்யப் பிழை திருத்தம் அவசியம்.
Key notes, relationships and model limits
Practical tip
Read voltage and current at several low-current settings and obtain resistance from the VI slope. Diameter measured with a screw gauge determines area; correct the ammeter zero.
Common trap
The slope of V against I gives resistance; obtaining resistivity also requires wire length and cross-sectional area.
Model limits
constant-temperature ohmic wire, ideal voltmeter, finite-resolution ammeter. No resistivity inferred at a zero corrected current; prolonged high current can heat real wires.
What you will learn
Adjust wire resistivity vi graph apparatus, observe its reading and derive the indicated physical quantity.
Try the experiment
Try both scenarios, change one control, and predict the result before checking the graph and readouts.
Think of it this way
Change one input while keeping the others fixed, as you would in a controlled experiment.
Worked example
For ρ=5×10⁻⁷ Ω m, L=1 m and d=0.2 mm, R≈15.92 Ω.
Why this matters
The model connects wire resistivity vi graph with an observable reading. Check the equation and assumptions before applying it.
Before you start
SI units · algebra · graph reading
Check your understanding
If wire length doubles at unchanged material and area, VI resistance?
- Halves.
- Doubles.
- Stays fixed because material resistivity is unchanged.
Read the explanation
Doubles.
Course connection: Virtual apparatus preparation. Check exact board/exam membership in the syllabus sources. Physical practical work remains necessary.