Question

Magnetic flux through a coil of resistance 10 $\Omega$ is changed by $\Delta\phi$ in 0.1 s. The resulting current in the coil varies with time as shown in the figure. Then $\left|\Delta\phi\right|$ is equal to (in weber)

• A. 6
• B. 4
• C. 2
• D. 8

Answer 1

Answer: (C)

As $e = \frac{\Delta\phi}{\Delta t}$ or $Ri = \frac{\Delta \phi }{\Delta t}\quad\left(\because e = Ri\quad\right)$
$\Rightarrow \quad\Delta \phi =R\left(i.\Delta t\right)$
$= R \times$ area under $i -1$ graph
$= 10\times \frac{1}{2}\times4\times0.1 = 2\,$ weber