Which of the following statements are correct about the electrical resistance and resistivity of a wire?
- 1. Both quantities depend on the area of cross-section of the wire
- 2. Both depend on the temperature
- 3. Resistance of the wire is directly proportional to the resistivity of the wire
- 4. Resistivity of the wire is directly proportional to the length of the wire
Select the correct answer using the code given below :
1 and 2
1 and 3
2 and 3
2 and 4
Answer is Right!
Answer is Wrong!
This question was previously asked in
UPSC NDA-2 – 2023
– Resistivity (ρ) is an intrinsic property of the material itself, depending on the material type and temperature, but not on the dimensions (length or area) of the specific wire.
– Statement 2: Both resistance and resistivity of most metallic conductors are dependent on temperature. For metals, both generally increase with increasing temperature. So, statement 2 is correct.
– Statement 3: From the formula R = ρ * (L/A), Resistance (R) is directly proportional to resistivity (ρ) for a wire of fixed length and area. So, statement 3 is correct.
– Statement 4: Resistivity (ρ) is a material property and does not depend on the length of the wire. So, statement 4 is incorrect.
– Thus, only statements 2 and 3 are correct.