The phenomenon of "Electromagnetic induction" was discovered by which scientist?

The working of a dynamo is based on the principle of

$A$ coil of effective area $3 \,m^2$ is placed at right angles to a magnetic field of induction $0.05 \,Wb/m^2$. If the field is decreased to $20 \%$ of its original value in $10 \,s$, the e.m.f. induced in the coil will be: (in $\,mV$)

$A$ coil of $n$ turns and resistance $R \ \Omega$ is connected in series with a resistance $R/2$. The combination is moved for time $t$ seconds through a magnetic flux change from $\Phi_1$ to $\Phi_2$. The induced current in the circuit is:

$A$ metal loop of area $10 \,cm^2$ is placed in a region such that its area vector points along $\hat{k}$. The region contains a uniform magnetic field of magnitude $1.73 \,T$ that points in the direction $\hat{i}+\hat{j}+\hat{k}$. When the magnetic field is switched off, the field decreases to zero at a steady rate in $10 \,s$, then the magnitude of emf induced in the loop is (in $\,mV$)

Two square wire frames $abcd$ and $efgh$ are placed in a uniformly decreasing magnetic field as shown in the figure. The direction of the induced current in both the loops is