Question

Define resistance of a conductor. State the factors on which resistance of a conductor depends.

Name the device which is often used to change the resistance without changing the voltage source in an electric circuit.

Calculate the resistance of 50 m length of wire of cross-sectional area 0.01 square mm and of resistivity 5 ×10 ^-8 ohm m​

Answer 1

Answer:

1. Resistance is the opposition offered in a path of flow of current by the atoms or molecules of the conductor.

Factors on which resistance of a conductor depends are:

• Length $R \propto l$

• Area of cross section $R \propto \dfrac{1}{A}$

• Nature of the material

2. Rheostat is used to change the resistance without changing the voltage source in an electric circuit.

3.

Given :

$\dashrightarrow l = 50 m$

$\dashrightarrow A = 0.01 {mm}^{2}$

$\dashrightarrow A = 0.01 \times {10}^{ - 6} \: {m}^{2}$

$\dashrightarrow \rho = 5 \times {10}^{ - 8} \: \Omega \: m$

We know that,

$\dashrightarrow R = \rho \dfrac{l}{A}$

$\dashrightarrow R = 5 \times {10}^{ - 8} \bigg(\dfrac{50}{0.01 \times {10}^{ - 6} } \bigg)$

$\dashrightarrow { \pink{ \underline{ R = 250 \: \Omega }}}$

Answer 2

The resistance of a conductor is the opposition to the flow of current and depends on the length and area of the material

What is resistance of a conductor?

Resistance is the opposition to the flow of current by the atoms or molecules of the conductor.

The factors on which resistance of a conductor depends are:

• Length of material
• cross-sectional area of the material
• Nature of the material

A Rheostat is the device used to change the resistance without changing the voltage source in an electric circuit.

The resistanceis given as:

• R = resistivity × length/ area

Area = 0.01 square mm = 1.0 × 10^-8 square m

R = (50 × 5 ×10 ^-8 ohm m)/1.0 × 10^-8 square m

Resistance = 250 ohm

Therefore, resistance of a conductor is the opposition to the flow of current.

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