A potentiometer wire of length $$4 \mathrm{~m}$$ and resistance $$5 ~\Omega$$ is connected in series with a resistance of $$992 ~\Omega$$ and a cell of e.m.f. $$4 \mathrm{~V}$$ with internal resistance $$3 ~\Omega$$. The length of $$0.75 \mathrm{~m}$$ on potentiometer wire balances the e.m.f. of

Select the correct statement from the following.

End correction at open end for air column in a pipe of length '$$l$$' is '$$e$$'. For its second overtone of an open pipe, the wavelength of the wave is

In a stationary lift, time period of a simple pendulum is '$$\mathrm{T}$$'. The lift starts accelerating downwards with acceleration $$\left(\frac{\mathrm{g}}{4}\right)$$, then the time period of the pendulum will be