Maharashtra BoardEnglish MediumSTD 12 SciencePhysicsElectromagnetic Induction3 Marks
Question
When is the magnetic flux through an area element (i) maximum (ii) zero? Explain.
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Answer
When an area element $d A$ is placed in a magnetic field $\vec{B}$, the magnetic flux through the element is $ d \Phi_m=B(d A) \cos \theta $ where 8 is the angle between $\vec{B}$ and the area vector $\overrightarrow{d A}$. (i) The maximum value of $\cos \theta=1$ when $\theta=0$. Thus, from Eq. (1), the magnetic flux is maximum, $d \Phi_m=B(d A)_{\text {, }}$ when the magnetic induction is in the direction of the area vector. (ii) The minimum value of $\cos \theta=0$ when $\theta=90^{\circ}$. Then, the magnetic flux is minimum, $d \Phi_m$ $=0$, when the magnetic induction is perpendicular to the area vector.
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