Using de Broglie's hypothesis , explain with the help of a suitable diagram , Bohr's second postulate of quantisation of energy levels in a hydrogen atom.

What do you mean by energy levels of a hydrogen atom ?

With the help of a circuit diagram explain the function of a shunt used in a galvanometer.

Explain the origin of spectral lines of hydrogen from Bohr's postulates.

Explain with the help of a diagram, how you would construct a NOT gate by using an n-p-n transistor.

State the postulates of Bohr's model of hydrogen atom .

State the postulates of Bohr's model of hydrogen atom .

With the help of Bohr's theory, how will you determine the kinetic energy of hydrogen or hydrogen-like atoms?

The light from a clear blue portion of the sky shows a rise and fall of intensity when viewed through a polaroid which is rotated. Describe, with the help of a suitable diagram, the basic phenomenom/process which occurs to explain this observation.

Two long straight parallel conducts carrying steady currents I_(1) and I_(2) are separated by a distance d. Explain briefly with the help of suitable diagram, how the magnetic field due to one conductor acts on the other. Hence deduce the expression for the force acting between the two conductors. Mention the nature of this force.

Energy in the second energy state of hydrogen atom is E_2 . Then