The magnetic flux linked to a circular coil of radius $R$ is given by $\phi = 2t^3 + 4t^2 + 2t + 5 \; Wb$. The magnitude of the induced $emf$ in the coil at $t = 5 \; s$ is $.......... \; V$.

Use Lenz's law to determine the direction of induced current in the situations described by Figure:
$(a)$ $A$ wire of irregular shape turning into a circular shape;
$(b)$ $A$ circular loop being deformed into a narrow straight wire.

$A$ conducting ring is placed around the core of an electromagnet as shown in the figure. When key $K$ is pressed,the ring

Some magnetic flux is changed through a coil of resistance $10 \, \Omega$. As a result, an induced current is developed in it, which varies with time as shown in the figure (assuming a triangular pulse with base $0.1 \, s$ and height $4 \, A$). The magnitude of the change in flux through the coil in $Wb$ is:

An aluminium ring $B$ faces an electromagnet $A$. The current $I$ through $A$ can be altered. Which of the following statements is correct?

$A$ coil having an area $2\,m^2$ is placed in a magnetic field which changes from $1\,Wb/m^2$ to $4\,Wb/m^2$ in an interval of $2$ seconds. The $e.m.f.$ induced in the coil will be......$V$.