The magnetic intensity at the center of a long current carrying solenoid is found to be $$1.6 \times 10^{3} \mathrm{Am}^{-1}$$. If the number of turns is 8 per cm, then the current flowing through the solenoid is __________ A.

An organ pipe $$40 \mathrm{~cm}$$ long is open at both ends. The speed of sound in air is $$360 \mathrm{~ms}^{-1}$$. The frequency of the second harmonic is ___________ $$\mathrm{Hz}$$.

A current of $$2 \mathrm{~A}$$ flows through a wire of cross-sectional area $$25.0 \mathrm{~mm}^{2}$$. The number of free electrons in a cubic meter are $$2.0 \times 10^{28}$$. The drift velocity of the electrons is __________ $$\times 10^{-6} \mathrm{~ms}^{-1}$$ (given, charge on electron $$=1.6 \times 10^{-19} \mathrm{C}$$ ).

A nucleus with mass number 242 and binding energy per nucleon as $$7.6~ \mathrm{MeV}$$ breaks into two fragment each with mass number 121. If each fragment nucleus has binding energy per nucleon as $$8.1 ~\mathrm{MeV}$$, the total gain in binding energy is _________ $$\mathrm{MeV}$$.