The radial density distribution is given by
Malenka, Levinger and Kent have carried out calculation of for square wells of infinite and finite depth. The density falls off to zero smoothly at the edge for infinite walls, but faster than experimental results indicate. In the harmonic oscillators well the density is peaked at the centre and decreases
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Appeared in Year: 2016
The equation of a progressive wave moving on a string is . In this equation, are in centimeters and is in seconds. Calculate amplitude, frequency and velocity of the wave. It two particles at any instant are situated apart, what will be the phase difference between these particles?
For any type of wave, transverse or longitudinal.
We have the equation .
This can be put in the form
Since and , it takes the form
Comparing it with given equation, we find it to be of the form, where (amplitude),
Since and therefore
There, amplitude of the wave , frequency , velocity and
wavelength .
In a distance , the phase difference is given by
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Appeared in Year: 2007
Give the Boolean expression and the truth table for an XOR gate. Why NAND gates are called universal gates? Realise OR and XOR gates employing only NAND gates.
The circuit of an exclusive – OR gate is shown in Fig (1a). As obvious, there are two inputs and one output. The exclusive – OR operation is denoted by . Hence the expression for the output of the circuit is give as
Image of Exclusive or Gate
Image of Exclusive or Gate Symbol
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Appeared in Year: 2016
Why are NAND and NOR gates called universal gates? Give logic diagram, Boolean equation and truth table of a NAND gate.
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Appeared in Year: 2007
Describe Stern – Gerlach experiment. Explain how it demonstrate the discrete nature of the magnetic moment of atom.
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Appeared in Year: 2007
Describe briefly the concept of effective mass in semiconductors and explain the significance of negative effective mass.
The dynamical effective mass is given by the relation:
Insofar as the motion in an electric field is concerned, the block electron behaves like a free electron whose effective mass is given by (1)
The mass is inversely proportional to the curvature of the band; where the curvature is large – that is is large - the mass is small; a small curvature
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