The magnetic flux linked with a coil varies as $\phi = 3t^{2} + 4t + 9$. The magnitude of the emf induced at $t = 2 \text{ s}$ is: (in $\text{ V}$)

The magnetic flux through a coil of resistance $10\,\Omega$ changes. As a result,an induced current is developed in it,which varies with time as shown in the figure. The magnitude of the change in magnetic flux through the coil in webers is:

$A$ uniform magnetic field $\vec{B}$ is perpendicular to the plane of a circular loop of diameter $10 \text{ cm}$ formed from a wire of diameter $2 \text{ mm}$ and resistivity $2 \times 10^{-8} \Omega \text{ m}$. If a current of $11 \text{ A}$ is to be induced in the loop, then the rate at which $\vec{B}$ is to be changed is: (in $\text{ T s}^{-1}$)

The working of a dynamo is based on the principle of

Magnetic flux linked with a coil is $\phi = 5t^2 + 2t + 3$,where $t$ is in seconds and $\phi$ is in webers. At time $t = 1 \ s$,the value of the induced emf is . . . . . . $V$.

Assertion : Lenz's law violates the principle of conservation of energy.
Reason : Induced $emf$ always opposes the change in magnetic flux responsible for its production.