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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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Problems

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

what is force
Afework Reply
The different examples for collision
Afework
What is polarization and there are type
Muhammed Reply
Polarization is the process of transforming unpolarized light into polarized light. types of polarization 1. linear polarization. 2. circular polarization. 3. elliptical polarization.
Eze
Describe what you would see when looking at a body whose temperature is increased from 1000 K to 1,000,000 K
Aishwarya Reply
how is tan ninety minus an angle equals to cot an angle?
Niicommey Reply
please I don't understand all about this things going on here
Jeremiah Reply
What is torque?
Matthew Reply
In physics and mechanics, torque is the rotational equivalent of linear force. It is also referred to as the moment, moment of force, rotational force or turning effect, depending on the field of study.
Teka
Torque refers to the rotational force. i.e Torque = Force × radius.
Arun
Torque is the rotational equivalent of force . Specifically, it is a force exerted at a distance from an object's axis of rotation. In the same way that a force applied to an object will cause it to move linearly, a torque applied to an object will cause it to rotate around a pivot point.
Teka
Torque is the rotational equivalence of force . So, a net torque will cause an object to rotate with an angular acceleration. Because all rotational motions have an axis of rotation, a torque must be defined about a rotational axis. A torque is a force applied to a point on an object about the axis
Teka
When a missle is shot from one spaceship towards another, it leaves the first at 0.950c and approaches the other at 0.750c. what is the relative velocity of the two shipd
Marifel Reply
how to convert:m^3/s^2 all divided by kg to cm^3/s^2
Thibaza Reply
Is there any proof of existence of luminiferious aether ?
Zero Reply
mass conversion of 58.73kg =mg
Proactive Reply
is Space time fabric real
Godawari Reply
What's the relationship between the work function and the cut off frequency in the diagram above?
frankline Reply
due to the upthrust weight of the object varise with force in which the body fall into the water pendincular with the reflection of light with it
Gift
n=I/r
Gift
can someone explain what is going on here
falanga
so some pretty easy physics questions bring em
falanga
what is meant by fluctuated
Olasukanmi Reply
If n=cv then how v=cn? and if n=c/v then how v=cn?
Natanim
convert feet to metre
Mbah Reply
what is electrolysis
Mbah
Electrolysis is the chemical decomposition of electrolyte either in molten state or solution to conduct electricity
Ayomide
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Ayesha Reply
can someone help explain why v2/c2 is =1/2 Using The Lorentz Transformation For Time Spacecraft S′ is on its way to Alpha Centauri when Spacecraft S passes it at relative speed c /2. The captain of S′ sends a radio signal that lasts 1.2 s according to that ship’s clock. Use the Lorentz transformati
Jennifer
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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