| English | Resistance |
|---|---|
| Bahasa Melayu | Rintangan |
| 中文 | 电阻 |
Definition
The opposition of a component to the flow of electric current, equal to potential difference divided by current; measured in ohms (Ω).
In exam terms
Resistance is the opposition of a component to the flow of electric current. It is a scalar quantity with the symbol R and the SI unit ohm (Ω), where 1 Ω = 1 V A⁻¹.
The defining relationship is R = V ÷ I, where V is the potential difference across the component in volts (V) and I is the current through it in amperes (A). For example, if a p.d. of 6 V drives a current of 0.5 A through a resistor, its resistance is R = 6 V ÷ 0.5 A = 12 Ω.
A larger resistance means a smaller current for the same p.d., which is why long, thin wires have more resistance than short, thick ones.
Do not confuse it with resistivity
Do not confuse resistance with resistivity. Resistance R (in ohms) describes a particular piece of wire and depends on its length, cross-sectional area, material and temperature.
Resistivity (in ohm metres, Ω m) is a property of the material alone, independent of the size or shape of the sample. Two wires of the same material can have very different resistances but the same resistivity.
In Paper 2 this appears as define resistance, or a calculation using R = V ÷ I, often combined with Ohm's law. A question may also state how resistance changes when the length or thickness of a wire is changed, so link longer or thinner to higher resistance.
Source: DSKP KSSM Physics Form 4 and 5 (Versi English) (Bahagian Pembangunan Kurikulum (BPK), KPM)