Electricity | Class 10 Science Notes
By ConceptScroll Team · Published on 17 July 2026 · 3 min read
Electricity – this guide gives you a concise, exam-ready overview of Electricity from Class 10 Science, written by ConceptScroll editors and reviewed against the latest NCERT textbook.
11.5 FACTORS ON WHICH THE RESISTANCE OF A CONDUCTOR DEPENDS
The resistance of a conductor depends on three main factors: its length, the area of cross-section, and the nature of the material.
An activity is performed using different wires to observe how these factors affect resistance. When the length of the wire is doubled, the current halves, indicating resistance doubles. A thicker wire (larger cross-sectional area) allows more current, indicating lower resistance. Different materials with the same dimensions show different currents, indicating different resistivities.
Mathematically, resistance R is directly proportional to length l and inversely proportional to cross-sectional area A, expressed as R ∝ l / A. Introducing the constant of proportionality ρ (rho), called resistivity, we get R = ρ (l / A).
Resistivity is a characteristic property of the material, with SI unit ohm meter (Ω m). Metals and alloys have low resistivity (10^-8 to 10^-6 Ω m), making them good conductors. Insulators like rubber and glass have very high resistivity (10^12 to 10^17 Ω m).
Resistivity and resistance also vary with temperature.
Table 11.2 lists resistivity values for various materials, showing alloys generally have higher resistivity than pure metals. Alloys are preferred for heating elements because they do not oxidize easily at high temperatures.
This section explains the physical basis of resistance and introduces resistivity as a fundamental material property.
📊 Diagram: Figure 11.5 Electric circuit to study the factors on which the resistance of conducting wires depends; Table on page 9 (11×3) showing resistivity of various materials; Table on page 9 (4×3) showing resistivity of insulators.
🧪 Activity: Activity 11.3: Set up circuit with nichrome wire; vary length, thickness, and material; measure current; analyze effect on resistance.
🔗 Connection: This section leads to understanding how resistors combine in circuits and how total resistance is calculated.
Table on page 9 (11×3)
| Material | Resistivity (Ω m) | |
|---|---|---|
| Conductors | Silver | 1.60 × 10^{-8} |
| Copper | 1.62 × 10^{-8} | |
| Aluminium | 2.63 × 10^{-8} | |
| Tungsten | 5.20 × 10^{-8} | |
| Nickel | 6.84 × 10^{-8} | |
| Iron | 10.0 × 10^{-8} | |
| Chromium | 12.9 × 10^{-8} | |
| Mercury | 94.0 × 10^{-8} | |
| Manganese | 1.84 × 10^{-6} |
| Alloys | Constantan
Table on page 9 (4×3)
| Glass | 10^{10} - 10^{14} | |
|---|---|---|
| Insulators | Hard rubber | 10^{13} - 10^{16} |
| Ebonite | 10^{15} - 10^{17} | |
| Diamond | 10^{12} - 10^{13} | |
| Paper (dry) | 10^{12} |
Frequently asked questions
A resistance wire is stretched so as to double its length. Its new resistivity will have a magnitude
same as its original
The equivalent resistance of a series combination of two resistances is X ohm. If the resistance are of 10 ohm and 40 ohm respectively, the value of X will be
50 ohm
The magnitude of induced current and potential difference can be increased by
increasing the strength of magnet
Electrical resistivity of a given metallic wire depends upon
(d) nature of the material
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- हमारा पर्यावरण | Class 10 Science Notes
Clear NCERT-aligned notes on हमारा पर्यावरण for Class 10 Science.