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Key equations

Electrostatic energy for equilibrium separation distance between atoms U coul = k e 2 r 0
Energy change associated with ionic bonding U form = E transfer + U coul + U ex
Critical magnetic field of a superconductor B c ( T ) = B c ( 0 ) [ 1 ( T T c ) 2 ]
Rotational energy of a diatomic molecule E r = l ( l + 1 ) 2 2 I
Characteristic rotational energy of a molecule E 0 r = 2 2 I
Potential energy associated with the exclusion principle U ex = A r n
Dissociation energy of a solid U diss = α k e 2 r 0 ( 1 1 n )
Moment of inertia of a diatomic molecule with reduced mass μ I = μ r 0 2
Electron energy in a metal E = π 2 2 2 m L 2 ( n 1 2 + n 2 2 + n 3 2 )
Electron density of states of a metal g ( E ) = π V 2 ( 8 m e h 2 ) 3 / 2 E 1 / 2
Fermi energy E F = h 2 8 m e ( 3 N π V ) 2 / 3
Fermi temperature T F = E F k B
Hall effect V H = u B w
Current versus bias voltage across p-n junction I net = I 0 ( e e V b / k B T 1 )
Current gain I c = β I B
Selection rule for rotational energy transitions Δ l = ± 1
Selection rule for vibrational energy transitions Δ n = ± 1

Conceptual questions

Describe two main features of a superconductor.

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How does BCS theory explain superconductivity?

BSC theory explains superconductivity in terms of the interactions between electron pairs (Cooper pairs). One electron in a pair interacts with the lattice, which interacts with the second electron. The combine electron-lattice-electron interaction binds the electron pair together in a way that overcomes their mutual repulsion.

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What is the Meissner effect?

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What impact does an increasing magnetic field have on the critical temperature of a semiconductor?

As the magnitude of the magnetic field is increased, the critical temperature decreases.

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At what temperature, in terms of T C , is the critical field of a superconductor one-half its value at T = 0 K ?

T = 0.707 T c

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What is the critical magnetic field for lead at T = 2.8 K ?

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A Pb wire wound in a tight solenoid of diameter of 4.0 mm is cooled to a temperature of 5.0 K. The wire is connected in series with a 50 - Ω resistor and a variable source of emf. As the emf is increased, what value does it have when the superconductivity of the wire is destroyed?

61 kV

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A tightly wound solenoid at 4.0 K is 50 cm long and is constructed from Nb wire of radius 1.5 mm. What maximum current can the solenoid carry if the wire is to remain superconducting?

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Additional problems

Potassium fluoride (KF) is a molecule formed by an ionic bond. At equilibrium separation the atoms are r 0 = 0.255 nm apart. Determine the electrostatic potential energy of the atoms. The electron affinity of F is 3.40 eV and the ionization energy of K is 4.34 eV. Determine dissociation energy. (Neglect the energy of repulsion.)

U coul = −5.65 eV E form = −4.71 eV , E diss = 4.71 eV

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For the preceding problem, sketch the potential energy versus separation graph for the bonding of K + and Fl ions. (a) Label the graph with the energy required to transfer an electron from K to Fl. (b) Label the graph with the dissociation energy.

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The separation between hydrogen atoms in a H 2 molecule is about 0.075 nm. Determine the characteristic energy of rotation in eV.

E 0 r = 7.43 × 10 −3 eV

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The characteristic energy of the Cl 2 molecule is 2.95 × 10 −5 eV . Determine the separation distance between the nitrogen atoms.

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Questions & Answers

how can we say dirac equation is also called a relativistic equation in one word
preeti Reply
what is the electronic configration of Al
usman Reply
what's the signeficance of dirac equetion.?
Sibghat Reply
what is the effect of heat on refractive index
Nepal Reply
As refractive index depend on other factors also but if we supply heat on any system or media its refractive index decrease. i.e. it is inversely proportional to the heat.
you are correct
law of multiple
if we heated the ice then the refractive index be change from natural water
can someone explain normalization condition
Priyojit Reply
please tell
1 millimeter is How many metres
Darling Reply
1millimeter =0.001metre
The photoelectric effect is the emission of electrons when light shines on a material. 
Chris Reply
What is photoelectric effect
Amit Reply
it gives practical evidence of particke nature of light.
particle nature
photoelectric effect is the phenomenon of emission of electrons from a material(i.e Metal) when it is exposed to sunlight. Emitted electrons are called as photo electrons.
what are the applications of quantum mechanics to medicine?
application of quantum mechanics in medicine: 1) improved disease screening and treatment ; using a relatively new method known as BIO- BARCODE ASSAY we can detect disease-specific clues in our blood using gold nanoparticles. 2) in Genomic medicine 3) in protein folding 4) in radio theraphy(MRI)
Quantam physics ki basic concepts?
Laxmikanta Reply
why does not electron exits in nucleaus
Kabbo Reply
electrons have negative
Proton and meltdown has greater mass than electron. So it naturally electron will move around nucleus such as gases surrounded earth
.......proton and neutron....
excuse me yash what negative
coz, electron contained minus ion
negative sign rika shrestha ji
electron is the smallest negetive charge...An anaion i.e., negetive ion contains extra electrons. How ever an atom is neutral so it must contains proton and electron
yes yash ji
yes friends
koantam theory
yes prema
quantum theory tells us that both light and matter consists of tiny particles which have wave like propertise associated with them.
proton and nutron nuclear power is best than proton and electron kulamb force
what is de-broglie wave length?
plot a graph of MP against tan ( Angle/2) and determine the slope of the graph and find the error in it.
Ime Reply
expression for photon as wave
Are beta particle and eletron are same?
Amalesh Reply
how can you confirm?
If they are same then why they named differently?
because beta particles give the information that the electron is ejected from the nucleus with very high energy
beta particle is of two kind beta plus and beta minus ,beta minus is electron and beta plus is positron
beta particles are none but positive charged electron
which is ejected from nucleus
when nutron converts to proton it splits to two part one proton and the minus part ejected as beta
both are same things only the difference is that beta partical ejected from the neuclus and electrons revolves round the neuclus.
what is meant by Z in nuclear physic
Shubhu Reply
atomic n.o
no of atoms present in nucleus
miss sanjana your question is wrong...question should be no of nucleus present in an atom...and answer is 1...
Owaise is right
Z = number of protons in a nucleus of an atom
Note on spherical mirrors
Shamanth Reply
Practice Key Terms 6

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Source:  OpenStax, University physics volume 3. OpenStax CNX. Nov 04, 2016 Download for free at http://cnx.org/content/col12067/1.4
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