Show that the NAND gate is a universal gate.
ifos-2014-subject-08-005
Explain with the help of a neat diagram the structure of a n-channel FET and its IV characteristics. In what way is an FET different from a BJT ?
ifos-2014-subject-08-004
A silicon diode operates at a forward bias voltage of 0\cdot 4\text{ V}. Calculate the factor by which the current will be multiplied when the temperature is increased from 25^\circ\text{C} to 150^\circ\text{C} (\eta for \text{Si} = 2).
ifos-2014-subject-08-003
X-ray of wavelength 1\cdot 4\text{ \AA} is found to be Bragg reflected from (111) plane of an fcc structure. If the lattice parameter of the crystal is 5\text{ \AA}, find the angle at which the X-ray beam is incident on the (111) plane of the crystal.
ifos-2014-subject-08-001
Prove the following Boolean identity and draw its gates equivalent : Y = \bar{B}(A + C) + C(\bar{A} + B) + AC
ifos-2013-subject-08-005
In an operational amplifier, the amplifier gain is 10000. The input series resistance is 100\text{ k}\Omega and the feedback resistance is 500\text{ k}\Omega. If the input voltage is 1\text{ volt}, find the exact output voltage and percentage error considering an infinite gain for the amplifier.
ifos-2013-subject-08-004
What is a thermistor? Discuss static characteristics of a thermistor. What is its time constant?
ifos-2013-subject-08-003
Write down London second equation for superconductors. Explain how it accounts for the Meissner effect.
ifos-2013-subject-08-002
Can you comment from the above question whether you can use it to scan surface by microscopy?
ifos-2013-subject-08-001
For a simple cubic, a face centered cubic and a body centered cubic crystal, determine the atomic packing factor. How many atoms per \text{mm}^2 surface area are there in (100) plane for leads which has f.c.c. structure. The radius of the atoms is 0\cdot 174\text{ nm}.
ifos-2012-subject-08-001
A power supply using a full-wave rectifier is to provide 100\text{ mA} at 20\text{ V} with no more than 1\% ripple. Calculate the minimum value of smoothing capacitor used. Consider the diode resistance and the resistance of the secondary of the transformer as negligible. Also take ripple frequency as 50\text{ cycles per second}.
ifos-2012-subject-08-002
(i) What is De Morgan's law ? (ii) Simplify the Boolean expression A + AB + ABC + ABCD
ifos-2012-subject-08-006
The above circuit exhibits a MOSFET with a source resistor. It has V_T = 1\text{ V} and \mu_n C_{ox} (W/L) = 2\text{ mA/V}^2. Calculate the drain voltage. Also determine whether the transistor is in saturation or in the triode region.
ifos-2012-subject-08-005
What is Meissner effect ? Determine the magnetic susceptibility of a superconductor. Explain whether a superconductor exhibits perfect ferromagnetism, paramagnetism or diamagnetism.
ifos-2012-subject-08-004
A type I superconductor with T_c = 7\text{ K} has slope \frac{dB_c}{dT} = -25\text{ mT/K} at transition temperature T_c. Estimate its critical field at 6\text{ K}.
ifos-2012-subject-08-003
Using band theory of solids, explain whether the effective mass of an electron can be positive, negative as well as infinity. Explain the significance of negative mass.
ifos-2011-subject-08-002
Explain the basic structure and operation of an n-channel FET. How FET acts as an amplifier ? Explain.
ifos-2011-subject-08-005
Using OP-AMPs design an analog circuit to solve the following differential equation : \frac{d^2 v}{dt^2} + k_1 \frac{dv}{dt} + k_2 v = v_1(t) with \frac{dv_{(0)}}{dt} = 1\cdot 5\text{ V}; v_{(0)} = 2\cdot 0\text{ V}.
ifos-2011-subject-08-004
(i) What are intrinsic and extrinsic semiconductors ? Explain. (ii) How are n-type and p-type semiconductors obtained ?
ifos-2011-subject-08-003
How are the band structures of insulators and semiconductors similar ? How are they different ?
ifos-2011-subject-08-001