Explain the principle of a device that can build up high voltages of the order of a few million volts.Draw a schematic diagram and explain the working of this device. Is there any restriction on the upper limit of the high voltages set up in this machine? Explain.

Name the devic,e which is used as a voltage regulator. Draw the necessary circuit diagram and explain its working.

Draw a schematic diagram of a cyclotron. Explain the underlying principle and working , stating clearly the function of the electric and magnetic fields applied to the charged particle. Deduce an expression for the period of revolution and show that it does not depend upon the speed of the charged particle.

Name the semiconductor device that can be used to regulate an unregulated d.c. power supply. With the help of I-V characteristics of this device, explain its working principle.

A step up transformer converts a low input voltage into a high output voltage. Does it violate law of conservation of energy? Explain.

Draw a labelled diagram of Hertz's experiment set up to produce electromagnetic waves. Explain the generation of electromagnetic waves using this set up.

Explain, with the help of a schematic diagram, the principle and working of a Light Emiting Diode. What criterion is kept in mind while choosing the semiconductor material for such a device ? Write any two advantages of light emiting diode over conventional incandescent lamps.

Describe briefly, with the help of a lablled diagram, working of a step-up transformer. A step up transformer converts a low voltage in to high voltage. Does it not violate the principle of conservation of energy?