The resistance of a wire is directly proportional to the
Correct answer: A. Length of the wire.
- A. Length of the wire.
- B. Conductivity of the wire.
- C. Colour and texture of the wire.
- D. Area of cross section of the wire.
Explanation
The resistance of a wire is directly proportional to its length and inversely proportional to its cross-sectional area and the material's conductivity. In this question, the correct relationship with direct proportionality is the length of the wire. Option A correctly identifies this relationship. Option B is incorrect because it refers to conductivity, which is inversely related to resistance. Option C is irrelevant as color and texture do not influence resistance. Option D is incorrect because the area is inversely proportional to resistance.
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About Resistance and Resistivity
Resistance measures opposition to current in a conductor and follows R = V/I for an ohmic conductor, while resistivity is an intrinsic property of the material. Questions use R = ρL/A, examine effects of length, cross-sectional area and temperature, and distinguish resistance, resistivity, conductance and conductivity.
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