Question:

The length of the wire is doubled, Its conductance will

Updated On: Sep 8, 2023
  • remain unchanged
  • be halved
  • be doubled
  • be quadrupled
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The Correct Option is B

Solution and Explanation

Conductance is inverse of resistance. Conductance is given by $\sigma=\frac{1}{R}$ Substituting $R=\rho \frac{l}{A}$, we get $\sigma=\frac{A}{\rho l}$ If $A=$ constant, then we have $\sigma \propto \frac{1}{l} \Rightarrow \frac{\sigma_{2}}{\sigma_{1}}=\frac{l_{3}}{l_{2}}$ Substituting $l_{2}=2 l_{1}$, we get $\sigma_{2}=\frac{\sigma_{1}}{2}$ Therefore, conductance will be halved.
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Concepts Used:

Electromagnetic Induction

Electromagnetic Induction is a current produced by the voltage production due to a changing magnetic field. This happens in one of the two conditions:-

  1. When we place the conductor in a changing magnetic field.
  2. When the conductor constantly moves in a stationary field.

Formula:

The electromagnetic induction is mathematically represented as:-

e=N × d∅.dt

Where

  • e = induced voltage
  • N = number of turns in the coil
  • Φ = Magnetic flux (This is the amount of magnetic field present on the surface)
  • t = time

Applications of Electromagnetic Induction

  1. Electromagnetic induction in AC generator
  2. Electrical Transformers
  3. Magnetic Flow Meter