Resistivity of conductors and insulators

The idea

Metals and alloys have very low resistivity, about 10⁻⁸ to 10⁻⁶ Ω m, and are good conductors; insulators such as rubber and glass have about 10¹² to 10¹⁷ Ω m; resistance and resistivity vary with temperature.

A huge gap

The resistivity of a material says how strongly it resists current. Metals such as copper have a very low resistivity. Rubber and glass have a very high one.

How does the resistivity of an insulator such as glass compare with that of a metal?

• It is enormously larger, by many powers of ten
• It is only a little larger
• It is smaller

Sort the materials

Drag or tap each material into the group where it belongs.

Powers of ten apart

The two groups are separated by an enormous gap in resistivity. Both resistance and resistivity of a material also change with temperature.

Metals and alloys have very low resistivity, about 10⁻⁸ to 10⁻⁶ Ω m, and are good conductors. Insulators such as rubber and glass have resistivity of the order of 10¹² to 10¹⁷ Ω m. Both resistance and resistivity vary with temperature.

• Material | Resistivity (Ω m)
• Metals and alloys | 10⁻⁸ to 10⁻⁶
• Insulators such as rubber and glass | 10¹² to 10¹⁷

Notes

Metals and alloys have very low resistivity (about 10⁻⁸ to 10⁻⁶ Ω m) and are good conductors; insulators such as rubber and glass have about 10¹² to 10¹⁷ Ω m; resistance and resistivity vary with temperature.

Check yourself

Which range of resistivity belongs to metals and alloys?

Which materials have a resistivity of the order of 10¹² to 10¹⁷ Ω m?

What happens to the resistance and resistivity of a material when its temperature changes?

How does the resistivity of insulators compare with that of metals?

• About 10⁻⁸ to 10⁻⁶ Ω m — correct. Yes!
• About 10¹² to 10¹⁷ Ω m. That range belongs to insulators such as rubber and glass.
• Exactly zero. Even metals have a small resistivity, about 10⁻⁸ to 10⁻⁶ Ω m, though it is very low.
• Metals and alloys. Metals and alloys have very low resistivity, about 10⁻⁸ to 10⁻⁶ Ω m.
• Insulators such as rubber and glass — correct. Yes!
• Copper and aluminium. Copper and aluminium are metals, with very low resistivity.
• Neither changes. Both the resistance and the resistivity of a material vary with temperature.
• Only the resistance changes, the resistivity stays fixed. Both the resistance and the resistivity of a material vary with temperature.
• Both vary with temperature — correct. Yes!
• It is many powers of ten larger — correct. Yes!
• It is a little smaller. Insulators have a far higher resistivity than metals.
• It is about the same. Metals are about 10⁻⁸ to 10⁻⁶ Ω m and insulators about 10¹² to 10¹⁷ Ω m, which are very far apart.