Solve your IGNOU Doubts

Question:

b) Calculate the ratio of the surface temperatures of the stars A and B from the following data:

Star	Absolute magnitude	Redius (Re)
A	2	62
B	6	4

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Question:

Obtain the values of $\lambda$ for which the matrix:

Image ignouassignments-ignouacademy-com--p-doubts-21656

will be orthogonal.

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Question:

a) The distance of planet Jupiter from the Sun is 5 AU. Express this distance in light year and parsec.

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Question:

What are ferroelectric materials? Explain with the example of BaTiO3. How are they different from piezoelectric materials?

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Question:

Explain addition and condensation polymerization with an example of each.

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Question:

d) Discuss in brief the following: i) Synchrotrons ii) Counters

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Question:

c) Identify whether the following particles are leptons, baryons or mesons:

Image ignouassignments-ignouacademy-com--p-solve-79361

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Question:

Calculate the mass of boron required to make a silicon crystal with $10^{16}$ $cm^{-3}$ doping density, if the initial melt load of silicon is 50 kg. The density of silicon in the melt is 2.5 g $cm^{-3}$ and boron has an atomic weight of 10.8 u. Assume that the equilibrium segregation coefficient k0is constant throughout the growth process.

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Question:

Determine the magnetic moment of $Co^{2+}Fe^{3+}\,_2O_4$ which has an inverse spinel structure.

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Question:

Calculate the critical field which would destroy superconductivity at 3 K in Hg which has a critical temperature TC = 4.153 K and B_ac(0) = 0.0411 T.

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Question:

b) Establish the relation for binding energy per nucleon for $\begin{matrix} A\\Z \end{matrix}X$ nuclei. Calculate the value of binding energy per nucleon for $\begin{matrix} 68\\28 \end{matrix}Ni$ Given:

Mass of Ni : 63.9280 u

Mass of proton : 1.007825 u

Mass of neutron : 1.008665 u

Is this nucleus stable?

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Question:

a) A radioisotope P has a half-life of $3 \,s.\,At\,t=0,$ a given sample of this isotope contains 8000 atoms. Calculate (i) its decay constant, (ii) average life, (iii) the time $t_1$ when 1000 atoms of the isotope P remain in the sample, and (iv) number of

decays per second in the sample at $t=t_1s.$

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Question:

d) Obtain the average value of r of a hydrogen atom in its ground state.

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Question:

c) Obtain the ground state terms of Li and Si.

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Question:

b) State Moseley’s law. Using this law, obtain the frequency of an X-ray line when L to K transition takes place in a silver atom. Take $\sigma =3.$

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Question:

A semiconductor has the following parameters at temperature T = 300 K:

$\mathrm{E_{g}=1.40\ e V.\;\ m_{e}^{*}=0.1\ m_{e}\,\cdot m_{h}^{*}=0.5\ m_{e}.}$

Calculate the energy of the intrinsic Fermi level and the intrinsic carrier concentration.

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Question:

A 2-D square lattice has a side of 1.5 Å. Calculate the momentum and energy of the electron whose wave terminates at the boundary of the first Brillouin zone.

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Question:

A divalent bcc solid has a lattice constant of 4.5 Å. Calculate its Fermi energy.

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Question:

a) Calculate the mean kinetic energy and potential energy of the 1-dimensional oscillator in the ground state having angular velocity $\omega .$