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# Electric & Magnetic Fields

### Electric Field Problem

A proton is moving parallel to a uniform electric field. The electric field accelerates the proton and increases its linear momentum to 5.0 10-23 kg m/s from 1.5 10-23 kg m/s in a time of 6.0 10-6 s. What is the magnitude of the electric field?

### Electric Potential Point Charges

What is the electric potential at a distance 0.25 m away from a point charge of 1.0 x 10^-9 C? How much work is required to bring an identical charge from very far away up to this distance of 0.25 m from the first charge? Please show work with correct answer.

### Magnetization in Terms of the Partiton Function

Why do we need to take the derivative of Log(Z_N) with respect to beta when computing the magnetization?

### Charge plate in an ionic solution

The situation is as follows: Put a charged plate in a solution - the sign of the charge doesn't matter - in response, counterions will form in the solution such that - at infinite - the total electric field cancels. However, nearer the plate, you have a distribution of these counterions that is determined by the potential - V

### Electric Fields

1. A point charge q produces an electric field of magnitude 90.5 N/C at a distance of 1.68 m. If the field is directed towards the charge, what is the value of q? 2. When the plates of a radio capacitor are charged with 0.18 mC, the potential between them is 9.0 V. What is the capacitance? 3. A pair of parallel plates is s

### Drawing and Computing Electric Field

Please assist me with the attached electric field [map] problem.

### Calculate the electric field everywhere.

A spherically symmetric charge density occupies the region r<a. The charge density increases with radius as rho(r)=(rho,o)r^2 where rho,o is a constant. Calculate the electric field everywhere.

### Charge density must be applied to the floor to float a person

A reasonable upper limit on the amount of charge that can be safely applied to a person is 1 micro Coloumb. What charge density must be applied to the floor to float a person with mass 50 kg and charge 1 micro Coloumb? Model the floor as an infinite plane with uniform surface charge density.

### Parallel plate capacitor

A parallel-plate capacitor is connected to a battery that maintains potential difference V between the plates. If the plates of the capacitor are pulled farther apart, do the following quantities increase, decrease, or remain the same? (a) Electric field between the plates; (b) charge on the plates; (c) capacitance; (d)

### Electrical Potential Energy

Hi. Can someone please tell me if I've gotten the right answer to this problem? A computer monitor accelerates electrons and directs them to the screen in order to create an image. If the accelerating plates are 1.2 cm apart, and have a potential difference of 25,000 V, what is the magnitude of the uniform electric field betw

### Electric Field: Solving for Force

Hi, I need some assistance understanding how to solve the following problem. Problem: A +5.0 micro-Coulomb charge experiences a 0.20 N force in the positive y direction. If this charge is replaced with a -2.7 micro-Coulomb charge, what force will it experience?

### Least Squares Lines

Please see attached file.

### Inductance of a short coil

I have the inductance of the long coil which is L=( Meu (not)* N^2 * A ) / (D) A = Area , D = Length , N = number of turns in the coil I need to prove that for a short coil the inductance (L) is the following: L =[( Meu (not)* N^2 * A ) / (D)] * [ [{(D^2 - a^2)^(1/2)} - a ] / (D)] ] a = radius of the coil A = 3.14 a^

### Dipole and work of moving positive charge

How much work is done moving a unit positive charge form 1 point of a triangle to another in the field of a dipole p? The triangle has the angles 45,45,90 with a base of length a. The dipole is located at the right base corner pointing in the -x direction. The positive unit charge has to be moved from the left corner to the t

### Perturbation Theory with Atoms

See attachment for better symbol representation. When an atom is placed in a uniform external electric field Eext, the energy levels are shifted - a phenomenon known as the stark effect. In this problem we analyze the stark effect for the n=1 and n=2 states of hydrogen. Let the field point in the z direction, so the potent

### Magnetic Force

A wire 2.80 m in length carries a current of 5.00 A in a region where a uniform magnetic field has a magnitude of 0.390 T. Calculate the magnitude of the magnetic force on the wire assuming the angle between the magnetic field and the current is (a) 60.0, (b) 90.0, (c) 120.

### Magnetic Field Strength

A piece of copper wire has a resistance per unit length of 6.45E-3 omega/m. The wire is wound into a thin, flat coil of many turns that has a radius of 0.170 m. The ends of the wire are connected to a 12.0 V battery. Find the magnetic field strength at the center of the coil. Answer in T.

### Moment and Maximum Torque

A circular coil of wire has a radius of 0.14 m. The coil has 80 turns and a current of 15 A, and is placed in a magnetic field whose magnitude is 0.30T. Determine the moment and maximum torque it can experience.

### Determining how Far a Point of Specific Magnetic Field Strength is from a Current-Carrying Wire

A long, straight wire carries a current of 48 A. The magnetic field produced by this current at a certain point is 7.0E-5 T. How far is the point from the wire? Answer in meters.

### The Radius of a Circular Path

Question: Suppose that an ion source in a mass spectrometer produces doubly ionized gold ions (Au2+), each with a mass of 3.27, 10-25 kg. The ions are accelerated from rest through a potential difference of 1.30 kV. Then, a 0.490 T magnetic field causes the ions to follow a circular path. Determine the radius of the path in mete

### Question about Potential Difference

A uniform electric field of magnitude 250 V/m is directed in the positive x direction. A +12.0 micro coloumb charge moves from the origin to the point (x, y) = (20.0 cm, 50.0 cm). a) What is the change in the potential energy of the charge-field system? b) Through what potential difference does the charge move?

### Physics - Electric Field

Electric Field Four identical point charges (q = + 10.0 micro coulomb) are located on the corners of a rectangle. The dimensions of the rectangle are L = 60.0 cm and W = 15.0 cm. Calculate the magnitude and direction of the resultant electric force exerted on the charge at the lower left corner by the other three charges.

### Magnetic field due to current in parallel wires

A long horizontal wire carries a current of It = 49.4 A. A seond wire (I), made of 2.30mm diameter copper wire and parallel to the first but L=17.6cm below it, is held in suspension magnetically. What is the current in the lower wire? use right as positive direction.

### Magnetic Field

A particle of charge 6e enters a region containing a magnetic field with a velocity of 7.5 X 105 m/s that is perpendicular to the field. There is a force on the particle of 6.84 X 10-13 N. Find the magnetic field T.

### Electric Force

Three charges are placed on the x and y axes as follows:+2q at the origin (0,0); -q at (a,0); +q at (0,a). Find the magnitude and direction of the electric field at the point (a/2,a/2), mid-way between the +q and -q charges.

### Electricity

What is the electric field at a point midway between a -7.67 micro coulombs and a +4.69 micro coulombs charge 3.65 cm apart? Take the direction towards positive charge to be positive.

### A conducting sphere with potential V is half embedded in a dielectric material. What is the surface charge density?

See attached file for full problem description.

### Physics: Magnetic field loop changes; does induced current run clockwise or counterclockwise

See the attached file for the figure. A) Give a counterexample to show that the following statement is false: "When the magnetic field through a loop changes, currents run in the loop in such a way as to make a new magnetic field in the opposite direction to the original one." (b) Two metal rings lie side by side on a tabl

### Free Particle Question

Consider an otherwise free particle with charge q moving in a uniform magnetic field whose field vectors are B. For the sake of simplicity, let's orient our reference frame so that the magnetic field points entirely in the z direction. a) The component definition of the cross product specifies that (see attached) b) Sh

### Magnitude and direction of magnetic field of a wire carrying a 20-A current

See attached file for problem E7S.7 What are the magnitude and direction of the magnetic field?