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# Electricity & Magnetism

### The drift velocity and Hall voltage.

The number density of free electrons in copper is 8.47 x 10 ^22 electrons per cubic centimeter. If a metal strip of copper 2 cm by 0.1 cm (thickness), magnetic field pointing up to top of paper, and a current og 10A, fins a) the drift velocity Vsubd and b) the Hall voltage (Assume the magnetic field is 2.0 T.)

### Motion of electrons in electric and magnetic fields.

A beam of electrons, such as in a computer monitor CRT, traveling in the X direction enters a region which has an electric field of 3,000 volts/meter directed in the Y direction and a magnetic field of 0.004 Tesla directed in the Z direction. The two separate forces are acting on the beam of electrons. The direction and magnitud

### Transistor by connecting two diodes back to back

Can we make a transistor by connecting two diodes back to back?

### Finding the force on the electron

An electron that has velocity v = (2.0 x 106 m/s)i + (3.0 x 106 m/s) j moves through the uniform magnetic field B = (0.030 T)i - (0.15 T)j. a) Find the force on the electron. b) Repeat your calculation for a proton having the same velocity.

### Electron in a magnetic field, Potential due to a charged rod

3) The uniform 30 mT magnetic field in figure 3 (see attachment) points in the positive z-direction. An electron enters the region of magnetic field with a speed of 5.0 * 10^6 m/s and at an angle of 30 degrees above the xy-plane. Find the radius "r" and the pitch "p" of the electron's spiral trajectory. 4) Figure 4 shows

### Complete the chart for each element

Element Atomic atomic atomic number of number number of name symbol number mass protons of neutrons electrons 1. He 2.krypton 3. 82 4. 31 5.

### Multipole expansion of the electric potential

Obtain an Approximate Electric Potential, Y (r), At a Large Distance, r >> a, From a Distribution Of Charges, Where the Multipole Expansion Of V (r) Includes Only the First Two Terms, the Monopole And the Dipole Term. See attached file for full problem description and diagrams.

### Simple waves problem

(See attached files for full problem descriptions) 1. a. What are the three longest wavelengths for standing waves on a 240 cm long string that is fixed at both ends? b. If the frequency of the second longest wavelength is 50 Hz, what is the frequency of the third longest wavelength? 2. A sheet of glass is coated with 500

### Motion of a charged particle in a constant electromagnetic field, Lorentz equation

The motion of a charged particle in an electromagnetic field can be obtained by the Lorentz Equation for the force on a particle in such a field. If the electric field vector is E and the magnetic field vector is B, the force on a particle of mass m that carries a charge q and has a velocity v is given by: F= qE + qv (cro

### Air line characteristic impedance

This is a multiple choice question on Air line characteristic impedance provided with full explanation. See attached question.

### Boundary conditions, dielectric constant

(See attached file for full problem description with proper symbols and equations) --- If there is a field described by the vectors A and B. These are related by =k where k is a constant. The two vectors are found to satisfy the differential equations 1) =0 2) =0 questions: 1. Using these relations derive the bou

### Using Divergence (Gauss) and Curl (Stokes) Theorems

See attached file for full problem description.

### Determining the Path and Center and Radius of Circles

Please check the attachment which contains the appropriate notation. A particle with charge q is at the origin and is given an initial velocity v=vox. The magnetic field in the origin is b=boz and the electric field is E=Eoy. Determine the path of the particle (that is, find its position as a function of time, and interpre

### Electrostatics and current carrying loop in magnetic field

** Please see the attached files for the full problem description **

### Diffraction in imaging system

Explain succintly the role diffraction plays in the ultimate resolution of an imaging system.

### Work done in assembling a solid-uniformly charged sphere

(a) Calculate the work done in bringing a charged spherical shell of thickness dr from infinity up to enclose an existing charged sphere of radius r, both having uniform charge densities. (b) Integrate this expression to calculate the work done U, in assembling a solid sphere of radius 'a' of uniform charge density. U = 3kQ

### Electric and magnetic field problem

Four charges are moving with constant velocity v along the sides of a square as it is shown in attached the diagram. The side length is a. Determine the magnitude and direction of electric and magnetic fields by these charges at an instant when they are exactly in the middle between two consequent corners. Please explain how

### Disc in a Magnetic Field Conductivity

Given an aluminum disc of radius R, thickness d, conductivity , and mass density spins on its axis with initial velocity . It passes through poles of a magnet producing a magnetic field perpindicular to the disc over a small area A. With this initial speed how many revolutions will it make before coming to rest?

### Gravitational Field Inside and Outside a Spherical Shell

What is the gravitational field both inside and outside a spherical shell of inner radius b and outer radius a?

### Electromagnetic Waves:Wavelength, intensity, Amplitude, field

Sinusoidal electromagnetic wave with f=1.09E10 and field strength of B=1.2E-8T find: wavelength, Amplitude of Electric field, and Intensity

### Motion of a charge particle in Magnetic and electric field.

A positive ion with charge 4.8 x 10(-19) C is traveling at a speed of 3 x 10(7) ms(-1) above the earth's atmosphere from East to West along the equator. The earth's magnetic field runs North-South. 1) Draw a sketch showing clearly the direction of motion of the charge, the lines of magnetic force and the direction of the magn

### Two-Dimensional Kinematics

Two cars lost in a blinding snowstorm are traveling across a large field, each thinking they are on the road, as shown in the figure on the left. They collide. If the distance x is 124 meters and the red car is travelling at 12.7 mph, how fast to the nearest hundredth of a mph was the blue car travelling? 10.37 mph? How do I fig

### Electric Current and Magnetism

I need some help with these question: Two long, straight wires are oriented perpendicular to the computer screen, as shown below, in which L = 4.5 cm. The current in one wire is I1 = 3.1 A, pointing into the screen, and the current in the other wire is I2 = 4.0 A, pointing out of the screen. Find the magnitude and direction of

### Electromagnetic Currents and Acceleration

Question: For an accelerating voltage of 900 V calculate the time taken for an electron to reach the anode after being accelerated from rest (u=0) at the cathode of a CRT. Anode -cathode separation is 1cm? Question: A wire carrying a current of 100 A due West in Australia is suspended between two towers 50 m apart. The lines

### Vogel's Birdfeeders: what is the Invested Capital?

Vogel's Birdfeeders has a cost of capital of 15%. The company's assets total \$3,000,000 and it has noninterest-bearing current liabilities of \$600,000. What is Vogel's invested capital?

### Megnetic effect of electric current: Field due to 4 wires.

"Consider the four current-carrying wires described in the figure below. Each of these wires is long and straight, and carries the current I either into or out of the page, as shown." What is the direction of the net magnetic field produced by these four wires at the center of the square? Please see attached for diagram.

### Charge-to-Mass Ratio of Charged Particle

A charged particle moves through a velocity selector at a constant speed in a straight line. The electric field of the velocity selector is 3.25 103 N/C, while the magnetic field is 0.360 T. When the electric field is turned off, the charged particle travels on a circular path whose radius is 4.20 cm. Find the charge-to-mass rat

### Electron Volt

What is the speed of a 300-eV proton? What is the speed of a 300-eV electron? Key: 2.40x10^5, 1.03x10^7

### Magnetic Field Increases at Constant Rates

In a region of space, the magnetic field increases at a constant rate. This changing magnetic field induces an electric field that (a) increases in time (b) is conservative (c) is in the direction of the magnetic field (d) has a constant magnitude. And why explain? Induced electric field E in Equation 31.9 (see attachment) is

### Crossed Electric and Magnetic Fields

Show how an undeflected trajectory for a moving charge is obtained with appropriate crossed E and B fields. Draw seperate diagrams to illustrate your answer for a positive charge and a negative charge.