Q14 of 330 Page 26

What do you understand by the "resistivity" of a substance?

The electrical resistivity of a material is also known as its specific electrical resistance. It is a measure of how strongly a material opposes the flow of electric current. A definition of resistivity is the electrical resistance per unit length and per unit of cross-sectional area.


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How does the presence of impurities in a metal affect its resistance?

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Fill in the following blanks with suitable words :

Resistance is measured in ............. The resistance of a wire increases as the length ...............; as the temperature ................; and as the cross-sectional area ............

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A wire is 1.0 m long, 0.2 mm in diameter and has a resistance of 10 Q. Calculate the resistivity of its material?

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Write down an expression for the resistance of a metallic wire in terms of the resistivity.