Electric charge is the physical property of matter that causes it to experience a force when placed in an electromagnetic field. There are two types of electric charge: positive and negative (commonly carried by protons and electrons respectively). Like charges repel each other and unlike charges attract each other. An object with an absence of net charge is referred to as neutral. Early knowledge of how charged substances interact is now called classical electrodynamics, and is still accurate for problems that do not require consideration of quantum effects.
Electric charge is a conserved property; the net charge of an isolated system, the amount of positive charge minus the amount of negative charge, cannot change. Electric charge is carried by subatomic particles. In ordinary matter, negative charge is carried by electrons, and positive charge is carried by the protons in the nuclei of atoms. If there are more electrons than protons in a piece of matter, it will have a negative charge, if there are fewer it will have a positive charge, and if there are equal numbers it will be neutral. Charge is quantized; it comes in integer multiples of individual small units called the elementary charge, e, about 1.602×10−19 coulombs, which is the smallest charge which can exist freely (particles called quarks have smaller charges, multiples of 1/3e, but they are only found in combination, and always combine to form particles with integer charge). The proton has a charge of +e, and the electron has a charge of −e.
Electric charges produce electric fields. A moving charge also produces a magnetic field. The interaction of electric charges with an electromagnetic field (combination of electric and magnetic fields) is the source of the electromagnetic (or Lorentz) force, which is one of the four fundamental forces in physics. The study of photon-mediated interactions among charged particles is called quantum electrodynamics.The SI derived unit of electric charge is the coulomb (C) named after French physicist Charles-Augustin de Coulomb. In electrical engineering it is also common to use the ampere-hour (Ah). In physics and chemistry it is common to use the elementary charge (e as a unit). Chemistry also uses the Faraday constant as the charge on a mole of electrons. The lowercase symbol q often denotes charge.
Okay, say we have one positive point charge, and one negative point charge.
Their charge values are exactly opposite (q and -q).
And say we place them a certain distance apart and hold them there, maybe creating something like a point-charge capacitor. These point charges can hold and transfer...
Hello
In Walter Lewin's lecture while explaining the Leyden jar he says that the charge on the glass is 12 times more than that in the air gap.
How is this obtained ?
Basically there are 2 metal containers separated by a glass sheet. The air gap between the outer conductor and glass is 1...
Homework Statement
An electrostatic point charge of 1 Coulomb (C) placed symmetrically
between two infinitely/perfectly conducting parallel plates. These two infinitely large
conducting plates are parallel to the yz plane.The region between the two plates is designated as “Region A.” Starting...
Hey guys,
New here. It's been a while since I've done any physics. I've been playing around with some mental work in my head and I am trying to figure out why something doesn't work. I know it shouldn't work, but I can't figure out the why.
What I am talking about is utilizing similar charges...
Hello everybody and merry Christmas! Here is the text of the problem which has been puzzling me for the last few days: there are two charges distant d from one another and at distance a from a conducting plane. Find the electrostatic energy of the system.
The first thing I find pretty strange...
A hollow conducting sphere has no net charge. There is a positive point charge at the center of the spherical cavity within the sphere. You connect a conducting wire from the outside of the sphere to ground. Will you measure an electric field outside the sphere?
I know that since the electric...
In many articles authors describe FMM for particles.
e.g.
http://www.csci.psu.edu/seminars/fallnotes/fmm.pdf
http://www.umiacs.umd.edu/labs/cvl/pirl/vikas/publications/FMM_tutorial.pdf
In other articles authors describe FMM for charged surface.
How does these formulations relates?
Main...
In lecture 2 of http://oyc.yale.edu/physics/physics/fundamentals-of-physics-ii/content/class-sessions , around the 50 minute mark, the professor calculates the value of an electric field at a point (x,0,0) on the x-axis of a cartesian coordinate system. (The video can be rather slow loading, so...
Homework Statement
Capacitors C_1=6μF and C_2=2μF are first charged by connecting them in parallel across a 250V battery. The capacitors are then disconnected from the battery and connected positive plate to negative plate and negative plate to positive plate. Calculate their charges...
Homework Statement
There are three point charges, q1 has a magnitude of 3.00mC (the sign is not known) and is 5.0cm away from P and 13.0 cm away from q2. P is 12.0cm away from q2 and the three points form a triangle. The net electric field at point P is entirely in the negative y-direction...
Homework Statement
Two charges, q1 and q2, are separated by a distance r. Find the position at which a third charge, q3, can be placed so that the net electrostatic force on it is zero.
Homework Equations
Coulomb's Law:
F = (kq1q2)/r122 * (r12hat)
The Attempt at a Solution
I was...
Homework Statement
Below are seven arrangements of two electric charges. All of the charges are the same size, 20 C, but they are either positive or negative. Each figure also has a point labeled P that lies on a straight line with the two charges. The distance between any two items is all 5...
Homework Statement
I have a hollow conducting sphere with a charge on it, and I'm looking at the static situation. Where are the charges located?
Homework Equations
Gauss' Law
The Attempt at a Solution
A static situation, so no electric field inside the sphere, or charges would move...
Homework Statement
There are two balloons of charges +3.37mC and -8.21mC. The distance between the two balloons is 2.00m. Determine the force between the two balloons.
Homework Equations
The Attempt at a Solution
Here’s my work:
(9.0×10^9Nm^2/C^2)((3.37mC)(8.21mC)/(2.00m)^2)...
What the program needs to do is quite simple, the problem is that I lack the knowledge needed to program in matlab.
I know how to program in assembly and C++ and that's about it, this would not be a problem for me if my University gave formal courses in how to use Matlab.
Here is what the...
"Beta particles are high-energy, high-speed electrons or positrons emitted by certain types of radioactive nuclei such as potassium-40. The beta particles emitted are a form of ionizing radiation also known as beta rays. "
Negative charges also contain electrons, Beta particle are...
People usually use an electrostatic voltmeter for direct measurement.
I would like to know what kind of charges is on following high voltage circuits.
Will it be positive or negative charges?
Does anyone have any suggestions?
Thanks in advance for any suggestions
It seems as if the charge we have labelled the electron with has simply been inferred by comparing it to the proton, in which case it is pretty much exactly the opposite, so we give the proton and electron charges of +1 and -1 respectively.
This is fine, but when we get to the standard model...
Does anyone have any suggestions on what charge of static electricity is being applied into the material?
When this material is exposed to light the areas exposed lose the charge, Does anyone know what kind of process it is for losing the charge under light?
Thanks in advance for any...
Homework Statement
Two charges, q and q', are located respectively, inside and outside a hollow conductor. Charge q' experiences a force due to q, but not vice versa. Prove this statement and explain the apparently violation of Newton's third law. There is no net charge on the conductor...
1)A wire is carrying a current, i, in the positive y-direction. The wire is located in a uniform magnetic field, B, oriented in such a way that the magnetic force on the wire is maximized. The magnetic force acting on the wire, FB, is in the negative x direction. What is the direction of the...
Hello, I am Pauline!, this is my very first post, I am new to this, I've only been teaching my self this, so please don't be mean! my question is this: I've noticed some particles have a fraction of a charge for example, a up quark has a 2/3 charge and a down quark has -1/3 charge. how can there...
Consider an Argand diagram that shows the number line (positive and negative) and the imaginary plane of other possibilities.
As in, we have numbers that are positive and negative, and through complex numbers all of the polarities in between.
I am using this as an analogy, because we have...
Homework Statement
Charge Q1 is fixed to the ceiling by means of a spring with the spring constant D and is moved from its rest position (which is at y=h) by the two charges Q2. The gravitational force may be neglected.
a) Determine the resulting force on Q1 in dependency of y.
b) The...
So I found out today my credit card account has about $200 worth of charges I did not make. However, my card has been in my pocket the whole time.
How can this happen? If someone knew my SSN, how could they make charges without my card?
Homework Statement
Two point charges q1 and q2 are located on a straight line normal to a grounded (V=0) conducting plane. Choosing the z axis to go through the charges, q1 is at a distance z1 above the conductor, and q2 is at a distance z2.
Find the potential V(x,y,z) everywhere above...
Homework Statement
A 3.17 μC and a -2.19 μC charge are placed 3.65 cm apart. At what point along the line joining them is the electric field zero? Assume that the first charge is at the origin and the second charge is at +3.65 cm. Homework Equations
E = K(q) / r2
Ep = E1 + E2
0 = E1 + E2
-E1...
Homework Statement
Q1,Infinite uniform line charges of 5 nC/m lie along the x and y axes in free space. Find E at (a), P(0, 0 , 4); and (b), P (0 ,3 , 4)
Q2, Three infinite uniform sheets of charge are located in free space as follows: 3 nC/m2 at z= -4, 6 nC/m2 at z=1, -8 nC/m2 at z=4...
Homework Statement
Gauss' Law states:
∫∫ E.dS = ∫∫∫ div(E) dV = Qenc/ε₀
The proof is as follows (this is from Marsden's Vector Calculus 5e):
Let M be a elementary region in ℝ3. Then if (0,0,0) ∉ ∂M, we have:
∫∫∂M r.n/r3 dS
= 4π if (0,0,0) ∈ M
= 0 if (0,0,0) ∉ M
Construct a sphere of...
Homework Statement
Consider 2 charges located in the x-y plane; q1 of magnitude 5 mC (millicoulombs) is located at the origin, and q2 of unknown magnitude is located at (x,y) = (0.1, 0) (in metres). The electric field E at position (0.03, 0.05) is found to be entirely in the +y direction...
Today I was reflecting about the statement that increasing the distance between two large charged plates increases voltage, when I started to wonder what the behavior was near point charges (more voltage? as much? less?).
Q and -Q are charges. P1 and P2 are locations.
Q @ x=0m
P1 @ x=1m...
My physics textbook defines the electric potential energy of a system to be equal to the external work that must be done to assemble the system, bringing each charge in from an infinite distance. And then it goes on the explain an example:
"Figure 24-15 shows two point charges q1 and q2...
Homework Statement
Consider two point charges a distance 1.5 cm apart. These charges have an electric potential energy of -190 micro J. The total charge of the system (the sum of the two charges) is 26 nC. What is the charge of each point charge?
Homework Equations
Uelec = K*q1*q2/d...
Homework Statement
I attached a picture to make it easier...
Homework Equations
Coulomb's Law: F=k(q1*q2)/(r)^2
a^2+b^2=c^2
Charge properties
The Attempt at a Solution
I uploaded a picture of one of the cleaner sheets of work I used so far...Basically, I suppose I'm at a...
I am referring to this:
A brainwave hit me and I wondered the following:
If the moment when i unplug or switch it off (In my country they have a switch for added safety reason), the live wire happens to be at the peak of the AC curve, will my extension cord effectively become similar to a...
Homework Statement
The questions are based off of the diagram I attached.
First, I had to find the strength of the electric field due to each charge at (0 cm, 8 cm).
Now I need to find the total electric field (both magnitude and direction) at (0 cm, 8 cm) and the total electric potential...
Homework Statement
A point charge q1 = 4.10 nC is placed at the origin, and a second point charge q2 = -2.95 nC is placed on the x-axis at x =+ 20.0 cm. A third point charge q3 = 2.00 nC is to be placed on the x-axis between q1 and q2. (Take as zero the potential energy of the three charges...
Homework Statement
The problem is given in the attachment belowHomework Equations
(i)EA= Q/epsilon naught
(ii)Area of cylinder used = 2pi*r*L
(iii)The integral of E*dA =Q/4pi*epsilon naught
(iv) Llamda= Q/LThe Attempt at a Solution
Well I know I needed to choose a suitable Gaussian surface...
Homework Statement
Suppose that two balls are suspended by identical threads of length .10m anchored to the same point. The pith balls have different masses and charges. The charge of one is 2.0 X 10^-7 C and the other one is 6.0 X 10^-8 C. Both threads make a 25 degree angle at...
Is a hydrogen on an ethanol more or less positive than on a water molecule. I think the hydrogen is more positive on a water molecule, but I still don't understand why?
Could someone help me figure this out... please and thank you :wink:
Hi there. I did this problem, and I wanted to know if my solution is ok.
The problem says: Three equal charges are situated at the vertex of an equilateral triangle, and we want to cancel out the forces exerted by each other. What charge q' of opposite sign should be placed at the center of the...
A positive charge Q is on the y-axis at a distance a from the origin, and another positive charge q is on the x-axis at a distance b from the origin.
A) For what values(s) of b is the x-component of the force on q a minimum?
B) For what values(s) of b is the x-component of the force on q a...
Homework Statement
Consider three charges arranged as shown.
+ + -
1 2 3
What is the magnitude of the electric field
strength at a point 1.5 cm to the left of the
middle charge? The value of the Coulomb
constant is 8.98755 × 10^9N m2/C2.
Answer in units of N/C
q1=8.2 µC= 8.2*10^-6...
Three charged objects are arranged on a vertical line as shown
in the figure. The separation between charges is 3.0 cm.
a) If you wanted to find the force on charge C, which
fields would be relevant? Explain and calculate the
magnitude of this field. Which direction does it point?
b)...
Four identical point charges of q = 8.37 nC are at the four corners of a square with a side length of 11.2 cm as shown in the figure. (had to make it but same thing since I can't copy it)
q q
Q
q q
Edit: doesn't come out right when I post so imagen a square little q's on...
Homework Statement
Three point charges are located at the vertices of an equilateral triangle. The charge at the top vertex of the triangle is -4.4 µC. The two charges q at the bottom vertices of the triangle are equal. A fourth charge 2 µC is placed below the triangle on its symmetryaxis, and...
Homework Statement
Determine at what point or points (not including points at infinity) the electric field vanishes.
Homework Equations
The Attempt at a Solution
Well, this seems to be a conceptual question and as I must be missing the concept, I don't know how to attempt to...
Homework Statement
(a) Find the magnitude and direction of the net electrostatic force exerted on the point charge q3 in the figure below. Let q = +1.5 µC and d = 27 cm.
http://www.webassign.net/walker/19-31.gif
Homework Equations
The Attempt at a Solution
I found Fx = 1.7 N...
point charges in an electric field
Homework Statement
Problem: A +8.75 micro C point charge is glued to a frictionless table. It is tied to -6.5 micro C point charge by a 2.5 cm string (weightless and nonconducting). A uniform electric field of magnitude 1.85*10^8 N/C is directed parallel to...