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How resistance or resistivity changes with length and thickness

This type of question, asked 4 times: 2023, 2024, 2025, 2026. All 6 questions below, oldest first.

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  1. Question 1

    2023

    36 (a)
    (i) What is meant by resistance of a conductor ? Define its SI unit. (ii) List two factors on which the resistance of a rectangular conductor depends. (iii) How will the resistance of a wire be affected if its (1) length is doubled, and (2) radius is also doubled ? Give justification for your answer.

  2. Question 2

    2024

    26
    Two wires A and B of same material, having same lengths and diameters 0⋅20{\cdot}2 mm and 0⋅30{\cdot}3 mm respectively, are connected one by one in a circuit. Which one of these two wires will offer more resistance to the flow of current in the circuit ? Justify your answer.

  3. Question 3

    2024

    14
    In case of four wires of same material, the resistance will be minimum if the diameter and length of the wire respectively are

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  4. Question 4

    2025

    13
    A wire of length ‘l’ is gradually stretched so that its length increases to 3*l*. If its original resistance is R, then its new resistance will be :

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  5. Question 5

    2025

    32
    Resistance of a wire of length 1 m is 35 Ω35\,\Omega at 20°C. If the diameter of the wire is 0⋅20{\cdot}2 mm, determine the resistivity of the material of the wire at that temperature. How will the resistivity of the wire change if the length and diameter of the wire both are doubled ? Justify your answer. (Given that π=227\pi = \dfrac{22}{7})

  6. Question 6

    2026

    39 (B)
    (i) Define electrical resistivity of a material. (ii) How will the resistivity and resistance of a conducting wire change if the length and area of cross-section of wire both are doubled ? Justify your answer. (iii) Calculate the electric current flowing through a 4 Ω4\,\Omega resistor that produces 100 J of heat every second.