Honey bees also produce beeswax,which finds many uses in industry,such as:

$A$ bar magnet has a coercivity of $4 \times 10^3 \, A/m$. It is desired to demagnetize it by inserting it inside a solenoid $12 \, cm$ long and having $60$ turns. The current that should be sent through the solenoid is . . . . . . $A$.

The filiform apparatus is a characteristic feature of which of the following?

Compared to blood,our lymph has:

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

If three vectors $a, b, c$ satisfy $a + b + c = 0$ and $|a| = 3, |b| = 5, |c| = 7$,then the angle between $a$ and $b$ is ............ $^\circ$.