| English | Resistivity |
|---|---|
| Bahasa Melayu | Kerintangan |
| 中文 | 电阻率 |
Definition
A property of a material that measures how strongly it opposes the flow of current, independent of the size or shape of the sample; measured in ohm metres (Ω m).
In exam terms
Resistivity, symbol ρ, is a property of a material that measures how strongly it opposes the flow of current, independent of the size or shape of a sample. It is measured in ohm metres (Ω m) and is linked to resistance by R = ρL/A, where L is length and A is cross-sectional area.
A material with high resistivity, such as nichrome, makes a good heating element.
Example of correct use: rearranging gives ρ = RA/L, so a wire’s resistance rises if it is made longer (larger L) or thinner (smaller A).
Do not confuse it with…
Do not confuse resistivity with resistance. Resistivity ρ depends only on the material and its temperature, not on the dimensions of the sample; resistance R depends on the length and cross-sectional area as well as the material. Two wires of the same material have the same resistivity but different resistances if their lengths or thicknesses differ.
In Paper 2, an experiment may vary the length L of a wire and plot R against L; the gradient equals ρ/A, which lets you determine the resistivity.
Source: DSKP KSSM Physics Form 4 and 5 (Versi English) (Bahagian Pembangunan Kurikulum (BPK), KPM)