Which of the following is not correct?

In the given figure, the magnetic field at the centre will be:

The accessory glands of the human male reproductive system are:

If $f(x) = \frac{1}{x^2} \int_3^x (2t - 3f'(t)) dt$,then $f'(3)$ is equal to

The equation of the locus of $z$ such that $\left|\frac{z-i}{z+i}\right|=2$,where $z=x+iy$ is a complex number,is

Alternating current of peak value $\left(\frac{2}{\pi}\right) \text{ A}$ flows through the primary coil of a transformer. The coefficient of mutual inductance between the primary and secondary coil is $1 \text{ H}$. The peak $EMF$ induced in the secondary coil is (Frequency of $AC = 50 \text{ Hz}$): (in $\text{ V}$)