Assuming that the junction diode is ideal, the current in the arrangement shown in figure is

The equation of simple harmonic progressive wave is given by $Y=a \sin 2 \pi(b t-c x)$. The maximum particle velocity will be twice the wave velocity if

In a fundamental mode,the time required for the sound wave to reach upto the closed end of a pipe filled with air is ' $t$ ' second. The frequency of vibration of air column is

Two small drops of mercury each of radius ' $R$ ' coalesce to form a large single drop. The ratio of the total surface energies before and after the change is