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Flux & Flux Density

Flux comes from the Latin word fluxus which means flow. There are two common uses for the term flux. In the transport phenomena, flux is defined as the rate of flow of a property per unit area. Flux as a mathematical concept also represents the surface integral of a vector field. Both definitions of flux are based heavily on mathematics and differential calculus.

In the transport phenomena there are eight different types of transport fluxes. The eight include: momentum flux, heat flus, diffusion flux, volumetric flux, mass flux, radioactive flux, energy flus and particle flux. Each of these fluxes are vectors at each point in space and have a definite magnitude and direction. For incompressible flows, the divergence of the volume flux is zero.

The surface integral of flux is


F is the vector field

dA is the vector area of the surface A

The surface normal is directed usually by the right-hand rule. Once can consider the flux the more fundamental quantity and call the vector field the flux density. Often a vector field is frawn by curves following the flow. The magnitude of the vector field is then the line density. The flux through a surface is the number of lines. 

China State in Flux

I need help on writing a response discussing a state (China) that has been "in flux" between a democracy and another form of goverment over the past 20-25 years (an example might be Russia's struggle with establishing a democracy).

Magnetic circuit model: A second winding is added

The core illustrated in Fig. 13.51(a) is 1 cm thick. All legs are 1 cm wide, except for the right-hand side vertical leg, which is 0.5cm wide. You may neglect nonuniformities in the flux distribution caused by turning corners. a) Determine the magnetic circuit model of this device, and label the values of all reluctances in

Insulating material bombarded with electrons - charge density

In pdf format, please provide the following, the derivations of formulae. I will draw all the sketches myself: When a block of insulating material such as Lucite is bombarded with electrons, the electrons penetrate into the material and remain trapped inside. In one particular instance a 0.1 microampere beam bombarded an

Accrued Accounts Payable and VAT Taxes

Can someone take a look at the below explanations and let me know if I need to change how it is worded? Please make any suggestions you deemed as necessary. Thanks. 1 - "Decrease In the accrued Accounts Payable (A/P) account is due to larger A/P accrual in December 2008 of $2.0M vs. A/P accrual in May 2009 of $1.8M; larger

Heat transfer Using Reynolds Analogy

A circuit board with a dense distribution of integrated circuits (ICs) and the dimensions of 120mm by 120mm on a side is cooled by a parallel flow of atmospheric air with a velocity of 2 m/s. From wind tunnel tests under the same flow conditions , the average frictional shear stress on the upper surface is determined to be

Electrostatics: Charge, flux and Field.

The electric field strength 4.10 cm from a very wide charged electrode is 4000 N/C. What is the charge (in nC) on a 2.00-cm- diameter circular segment of the electrode?

Flux Analysis

Obtain the most recent financial statement of any company that you would like to research. Please state the name of the company, its business activity along with key financial data (sales, operating profit, net income, assets, liabilities and equity of this company). 2. Obtain the same information for one of company's compe

Magnetic Circuits

Given the relationship B/H=u H=IN/l and L=N*change in magnetic flux/change in coil current show that the inductance of a coil is: L=N^2/S where S=l/uA

Vector Fields

1 Calculate the divergence and curl of the vector field F(x,y,z) = 2xi+3yj+4zk. 2 Find the potential of the function for the conservative vector field: F(x,y,z) = (y+z)i + (x+z)j + (x+y)k. 3 Use Green's theorem to calculate the work done when a particle is moved along the helix x = cos t, y = sin t, z

Electric field and bounded charges on dielectric surfaces.

A uniformly charged straight wire of radius a carries linear charge density( lambda). The wire is coated with a linear dielectric material of susceptibility and external radius b. a. Find electric field everywhere b. Find the volume and surface bound charge densities

14 Modern Physics Questions

See attached file for full problem description. 1. A certain string on a piano is tuned to produce middle C (f = 261.63 Hz) by carefully adjusting the tension is the string. For a fixed wavelength, what is the frequency when this tension is doubled? a. 130.08 Hz b. 185.00 Hz c. 370.00 Hz d. 446.63 Hz e. 523.26 Hz 2

Magnetic Circuits: MMF and Reluctance

The magnetic circuit shown in figure below is built up of solid iron cross section, 1x1cm2. Each air gap is 1 mm wide. For this type of air gap, the effective cross-section of the air may be taken as 1.2 x that of iron path to allow for fringing. Two different grades of iron are used. When a coil having 2000 turns is wound on pa

Electrostatics: Unequal Charge density on parallel plates

(See attached file for full problem description) --- 1. Consider two infinite parallel plane conducting plates, of finite thickness, with separation d. Suppose a charge density of sigma; is placed on one plate, while the other plate has -2sigma. A) Determine the resulting charge densities on each of the 4 surfaces B) De

Current in a Loop

If the current in the loop of the attachment were halved, the total flux threading the loop would: 1) Halve 2) Be reduced to 1/4 of the previous value 3) Decrease to 3/4 of its original value 4) Decrease by more than 1/2 but greater than 1/4 its previous value.

Manufacturing Process for Making Steel

Please give a brief description on how steel is made that addresses the following: - What process is used (i.e. product focus, process focus or group technology/cellular manufacturing - Anything surprising in the process - Is there anything that is particularly interesting or creative about the process - How might this pr

Heat Flux Calculation: Copper Wire

Please see the attached file for the fully formatted problem(s). 1. A heated copper wire 1 mm in diameter is in a pool of water at 1 atm. What is the maximum heat flux (q/A)? The temperature difference is related to the heat flux (q/A) by the following equation: [Equation] What temperature difference (which we'll cal

DC Series Motor Question

When operating from a 230 V dc supply, a DC series motor operates at 900 rounds per minute with a line current of 75 Amps. Its armature-circuit resistance is 0.13 Ohms, and its series-field resistance is 0.09 Ohms. Due to saturation effects, the flux at an armature current of 25A is 45 percent of that at an armature current of

Flux and Current

Consider a point source emitting 10^12 neutrons/s in a vacuum. Calculate the flux and the current at a distance of 1 m from the source.

Flux of Space Regions Bounded

Consider the space region bounded below by the right angled cone z=sqrt(x^2+y^2), and above by the sphere x^2+y^2+z^2=2. These two surfaces intersect in a horizontal circle, let T be the horizontal disk having this circle as boundary, S the spherical cap forming the upper surface, and U the cone forming the lower surface.

Electrical Energy Conversion: Voltages & Currents

Question: Find the current I_N, required to establish a flux of 2 mWb in the air gap of the magnetic structure shown in the figure in the attached file. The structure is made of silicon sheet steel, and its magnetization curve is also shown. Assume that the coil has 500 turns, and the structure has the dimensions given in the at


Dry air will break down and generate a spark if the electric field exceeds about 2.95 x 10^6 N/C. How much charge could be packed onto a green pea (diameter 0.830cm) before the pea spontaneously discharges?

Flowing water: Volume of water that flows through this surface

See attached file for proper format. Consider a body of flowing water, such as a river. We can describe the flow of river water mathematically by a vector field that describes the water velocity v at every point in the river at an instant of time. Now imagine a small, flat surface submerged in the river. (If you want to visu

Calculating the Potential Difference

Question: Consider a generator constructed as shown in the attachment. The loop in this generator rotates at an angular rate of w. The slip rings in this design ensure that the same leg of the rotating loop is always connected to the same output terminal. Show that the potential difference between the output terminals is given b

Coaxial cable: magnitude of the electric field; capacitance of the cable

Neglect end effects. The region between the conductors is air. Ke =1/4*pi*epsilon= 8.98755e9 N m^2/C^2. A coaxial cable has a charged inner conductor (with charge +4.8 microcoulombs and radius 1.199 mm) and a surrounding oppositely charged conductor (with charge -4.8 microcoulombs and radius 7.405 mm). a) What is the magn