The resistance (R) of a wire is inversely proportional to its electrical conductivity (σ) for a given length (l) and area of cross-section (A). The formula is R = (1/σ) (l/A). Since both wires have the same length and area of cross-section, their resistances are directly proportional to their resistivities (ρ = 1/σ). We are given that the electrical conductivity of copper (wire 1) is more than that of aluminium (wire 2), i.e., σ_Cu > σ_Al. This implies that the resistivity of copper is less than that of aluminium (ρ_Cu
Two wires are made having same length l and area of cross-section A. Wire 1 is made of copper and wire 2 is made of aluminium. It is given that the electrical conductivity of copper is more than that of aluminium. In this context, which one of the following statements is correct?
Asked in UPSC CDS 2 2017 · Topic: Conductivity (Electrical Conductivity and Resistivity: Definitions, Units, and Ohm's Law)
Show answer
Answer: B. The resistance of wire 2 will be higher than that of wire 1.
More Physics questions
- A metal wire of length l and diameter d has a resistance R. What would be the resistance of another wire of the same metal and of same length but having double the diameter ?
- Which one of the following is the most appropriate reason for aircraft being equipped with conducting tyres ?
- The electrical resistance of a wire varies directly with its length and inversely with the square of its diameter. If a wire with a length of 200 cm and a diameter of one-quarter of a centimeter has a resistance of 20 ohms, find the electrical resistance in a 500 cm wire with the same diameter
- The product of conductivity and resistivity of a conductor
- Which one of the following correctly represents the SI unit of resistivity?
- Why are the tyres of aircrafts made of conducting rubber? 1. So that the charge accumulated on the aircraft in flight, by rubbing the air, can easily be transferred to ground on landing. 2. So that the charge accumulated due to the operation of various electronic equipments in the aircraft in flight can easily be transferred to ground on landing. Select the correct answer using the code given below.
- Which one of the following graphs correctly represents the current (I) – voltage (V) variation for a rectangular piece of a semiconductor wafer ?
- 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 :