The potential energy of a molecule on the surface of a liquid compared to one inside the liquid is

If the population grows at the rate of $8 \%$ per year,then the time taken for the population to be doubled is (Given $\log 2=0.6912$ ) (in $\text{ years}$)

The force between the plates of a parallel plate capacitor of capacitance $C$ and distance of separation of the plates $d$ with a potential difference $V$ between the plates,is

$A$ transformer works on the principle of

The maximum energy in the thermal radiation from a hot source occurs at a wavelength of $11 \times 10^{-5} \text{ cm}$. According to Wien's displacement law,the temperature of the source (on the Kelvin scale) will be $n$ times the temperature of another source (on the Kelvin scale) for which the wavelength at maximum energy is $5.5 \times 10^{-5} \text{ cm}$. The value of $n$ is: