A wire is stretched uniformly at a constant temperature without changing its material. Which of the following physical quantities remains unchanged?
Resistivity
Resistivity (specific resistance) ρ is a property of the material and its temperature only; it does not depend on the length or shape of the wire.
When the wire is stretched uniformly at constant temperature, its material and temperature are unchanged, so ρ stays the same.
Stretching increases the length and, since the volume stays constant, reduces the cross-sectional area. As \(R = \frac{\rho L}{A}\), the resistance increases.
Hence, the answer is Resistivity.
Similar Questions
When a cylindrical wire made of a new alloy is stretched to double its original length, its resistance increases by a factor of four. If a second wire of the same alloy is shaped into a flat ribbon of identical length but half the original cross-sectional area, which property stays constant between the two wires?
The SI unit of resistivity is:
Which of these changes would decrease the resistance of a metallic conductor?
Important Questions from Resistance and Resistivity
Which of the following metals has the lowest electrical resistivity?
A uniform wire of resistance 9Ω is bent in the form of an equilateral triangle. Find the effective resistance across a side of the triangle.
The value of carbon resistance is 54 × 103 Ω. The percentage tolerance is 5%. What is the colour code sequence of carbon resistance?
Which of the following relations are wrong?
I. The specific conductance is given by the relation \(k = \frac{1}{R}\left( {l/A} \right)\)
II. The equivalent conducting is given by the relation \(\lambda = \frac{{100\;K}}{C}\)
III. The specific resistance is given by the relation \(\rho = \frac{{Rl}}{A}\)
A current is flowing through a metallic wire. If the wire is heated, which quantities change?
