The moment of inertia of a thin circular lamina of mass $1\,kg$ and diameter $0.2\,m$ rotating about one of its diameters is:

If the peak value of the magnetic field of an electromagnetic wave is $30 \times 10^{-9} \ T$,then the peak value of the electric field is (in $Vm^{-1}$)

The vectors $\vec{AB} = 3\hat{i} - 2\hat{j} + 2\hat{k}$ and $\vec{BC} = \hat{i} - 2\hat{k}$ are the adjacent sides of a parallelogram. The angle between its diagonals is

$A$ potential difference of $20 \ kV$ is applied across an $X-ray$ tube. The minimum wavelength of $X-rays$ generated (in $\mathring{A}$) is

$A$ ball is dropped from a height of $20 \ m$ above the surface of water in a lake. The refractive index of water is $4/3$. $A$ fish inside the lake, in the line of fall of the ball, is looking at the ball. At an instant, when the ball is $12.8 \ m$ above the water surface, the fish sees the speed of the ball as ........ $m/s$ $[g = 10 \ m/s^2.]$