A step up transformer operates on $$220 \mathrm{~V}$$ and supplies current of $$2 \mathrm{~A}$$. The ratio of primary and secondary windings is $$1: 20$$. The current in the primary is

The ratio of maximum to minimum wavelength in Balmer series of hydrogen atom is

The work done in blowing a soap bubble of volume '$$\mathrm{V}$$' is '$$\mathrm{W}$$'. The work required to blow a soap bubble of volume '$$2 \mathrm{~V}$$' is [$$\mathrm{T}=$$ surface tension of soap solution]

A current carrying loop is placed in a uniform magnetic field. The torque acting on the loop does not depend upon