If the function

$$f(x)= \begin{cases}\frac{1}{|x|}, & |x| \geqslant 2 \\ \mathrm{a} x^2+2 \mathrm{~b}, & |x|<2\end{cases}$$

is differentiable on $$\mathbf{R}$$, then $$48(a+b)$$ is equal to __________.

The ratio of the magnitude of the kinetic energy to the potential energy of an electron in the 5^th excited state of a hydrogen atom is :

The work function of a substance is $$3.0 \mathrm{~eV}$$. The longest wavelength of light that can cause the emission of photoelectrons from this substance is approximately;

Primary coil of a transformer is connected to $$220 \mathrm{~V}$$ ac. Primary and secondary turns of the transforms are 100 and 10 respectively. Secondary coil of transformer is connected to two series resistances shown in figure. The output voltage $$\left(V_0\right)$$ is :