Question

A $10\text{m}$ long horizontal wire extends from North East to South West. It is falling with a speed of $5.0\text{m/s}$, at right angles to the horizontal component of the earth's magnetic field of $0.3\times {10}^{-4}{\text{Wb/m}}^2$. The value of the induced emf in wire is:

• A. $2.5\times {10}^{-3}\text{V}$
• B. $0.3\times {10}^{-3}\text{V}$
• C. $1.5\times {10}^{-3}\text{V}$
• D. $1.1\times {10}^{-3}\text{V}$

Answer 1

The correct option is C $1.5\times {10}^{-3}\text{V}$

When a conductor moves in the magnetic field, a motional emf will be induced.

$\text{Here,}B,l\text{and}v$ are mutually perpendiular,

Therefore, the motional emf is given by,

$E=Bvl$
$\Rightarrow E=0.3\times {10}^{-4}\times 5\times 10$
$\Rightarrow E=1.5\times {10}^{-3}\text{V}$

Hence, option $\left(A\right)$ is correct.