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Question

The length and the cross-sectional area of a conductor in the shape of a cylinder are '\(l\)' and '\(A\)' respectively. The resistivity of the material of the conductor is '\(\rho\)'. Its resistance depends upon
(p) \(l\) only
(q) \(l\) and \(A\)
(r) \(\rho\), \(l\) and \(A\)
(s) \(\rho\) and \(l\), but not \(A\)
Pick up the right option from those given above.

This question was previously asked in
RRB ALP 2018 CBT 2 Fitter Question Paper (21-Jan-2019) (Shift 3)
The correct answer is
(r)

Conductor Resistance Factors: Formula and Dependence

The resistance (\(R\)) of a conductor depends on its material properties and physical dimensions. For a cylindrical conductor of length '\(l\)' and cross-sectional area '\(A\)', the resistance is given by the formula:

\(R = \rho \frac{l}{A}\)

Here, '\(\rho\)' represents the material's resistivity, '\(l\)' is the conductor's length, and '\(A\)' is its cross-sectional area. The formula indicates that resistance is directly proportional to both resistivity and length, and inversely proportional to the area. Therefore, resistance is influenced by \(\rho\), \(l\), and \(A\).

Resistance Factors: \(\rho\), \(l\), and \(A\) Dependence

Analyzing the resistance formula \(R = \rho \frac{l}{A}\) clarifies the dependencies:

  • The resistance (\(R\)) is directly proportional to resistivity (\(\rho\)).
  • The resistance (\(R\)) is directly proportional to length (\(l\)).
  • The resistance (\(R\)) is inversely proportional to the cross-sectional area (\(A\)).

Consequently, the resistance depends on all three parameters: \(\rho\), \(l\), and \(A\). This matches option (r).

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Similar Questions

  1. If the length of a resistor is doubled, what happens to its resistance, assuming all other factors remain constant?

  2. The resistance of a particular material wire with length L and cross-sectional area A is 2 Ω. What would be the resistance of another wire of the same material having length 2L and area of cross-section A/2?
  3. Which of the following factors affect(s) the resistance of a wire?
  4. The resistance of a uniform metallic conductor depends on its:
  5. Which of the following statements is correct?
  6. A cylindrical wire of length L and radius r has resistance R. The resistance of another wire of the same material but of twice its length and one-fourth its radius is:

  7. A cylindrical wire of length L and radius r has a resistance R. The resistance of another wire of the same material but half its length and half its radius will be:
  8. Resistivity of the wire depends on mainly ________
  9. The resistance of a metallic wire of length 1m and area of cross-section 1sq.metre having a resistivity is $2 \times 10^{-6}$ ohm - m is:
  10. A cylindrical wire of length \(L\) and radius \(r\) has a resistance \(R\). The resistance of another wire of same material but having four times its length and half its radius will be:

Important Questions from Resistance and Resistivity

  1. Which of the following metals has the lowest electrical resistivity?

  2. When electric current is passed through a wire, the amount of heat produced in a wire depends upon _______.

    I. Length

    II. Thickness

  3. 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.

  4. The value of carbon resistance is 54 × 103 Ω. The percentage tolerance is 5%. What is the colour code sequence of carbon resistance?

  5. 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 \(\rho = \frac{{Rl}}{A}\)

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