Short Answer TypeMention the function of any two of the following used in communication system:
(i) Transducer (ii) Repeater
(iii) Transmitter (iv) Band pass Filteri) Transducer: A device which converts energy from one form to another form. It is used in microphone for converting sound energy into electrical energy and vice-versa.
ii) Repeater: It is a combination of a receiver and a transmitter. It is used in transmission system to regenerate the signal by picking up a signal, amplifying it and then transmitting it to the receiver.
iii) Transmitter: A device which processes the incoming message signal so as to make it suitable for transmission through a channel and for its subsequent reception.
iv) Bandpass filter: A device which allows only signals of a certain frequency range and blocks the rest of the frequencies. It is used in an electronic filter.
The current in the forward bias is known to be more (~mA) than the current in the reverse bias (~ A). What is the reason, then, to operate the photodiode in reverse bias?
(a) Using Bohr’s second postulate of quantization of orbital angular momentum show that the circumference of the electron in the nth orbital state in hydrogen atom is n times the de Broglie wavelength associated with it.
(b) The electron in hydrogen atom is initially in the third excited state.
What is the maximum number of spectral lines which can be emitted when it finally moves to the ground state?(i) What characteristic property of nuclear force explains the constancy of binding energy per nucleon (BE/A) in the range of mass number ‘A’ lying 30 < A < 170?
(ii) Show that the density of nucleus over a wide range of nuclei is constant- independent of mass number A.Write any two factor which justify the need for modulating a signal.
Draw a diagram showing an amplitude modulated wave by superposing a modulating signal over a sinusoidal carrier wave.Write Einstein’s photoelectric equation. State clearly how this equation is obtained using the photon picture of electromagnetic radiation.
Write the three salient features observed in photoelectric effect which can be explained using this equation.a) Why are coherent sources necessary to produce a sustained interference pattern?
(b) In Young’s double slit experiment using monochromatic light of wavelength 
, the intensity of light at a point on the screen where path difference is 
is K units. Find out the intensity of light at a point where path difference is 
.
Use Huygen’s principle to explain the formation of diffraction pattern due to a single slit illuminated by a monochromatic source of light.
When the width of slit is made double the original width, how this affect the size and intensity of the central diffraction band?
Long Answer TypeExplain 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.
(a) Define electric flux. Write its S.I. units.
(b) Using Gauss’s law, prove that the electric field at a point due to a uniformly charged infinite plane sheet is independent of the distance from it.
(c) How is the field directed if (i) the sheet is positively charged, (ii) negatively charged?
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