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What is electrical resistivity of a material? What is its unit? Describe an experiment to study the factors on which the resistance of conducting wire depends.
The electrical resistivity of a material is defined as the of a conductor of unit length and unit . The SI unit of resistivity is .
The experiment requires a cell, wire, key, an ammeter, and a plug key.
1. Connect the cell, and key in using the wire of length and note the current value.
2. Replace the wire with another one of the thickness but and note the current.
3. Again, replace the wire with another one with thickness of the and note the current.
4. Repeat the experiment with a wire and note the current value.
From the above experiment, it can be observed that
- The current value when the length of the wire is .
- The reading is increased when a wire of the same length and material is used.
- When a wire of different materials of the same length and the area of cross-section are used, the reading .
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