# Search results

1. ### B Current in a circuit

If we measure the voltage in a simple series circuit to be 5v and the resistance to be 10 ohms. The current given is .5A. Is this the amount of chage traveling from the first point to the second point per unit time, or is it the amount of charge flowing through a cross section of the conductor...
2. ### Coefficient of kinetic friction lab

Homework Statement I need to find the coefficient of kinetic friction from a set a lab data that I found. I had a mass connected to a mass hanger by a pulley, and measured the acceleration of the mass with various amounts of mass on the hanger. In the attached image, the acceleration was...
3. ### B Meaning of Current in Ohm's law

If we had a parallel circuit with a voltage of V between the beginning and end, and the circuit has a resistance R, then the current given by ohms law is I = V/R. What does this mean? The current is not the same throughout the whole circuit. Where is the current equal to this value?
4. ### I Improper integrals

I understand what improper integrals are, but are they really integrals? The semantics are just a bit confusing.
5. ### B Ohmic and non-Ohmic conductors

Do ohmic conductors obey ohms law at high voltages? Also, I’ve seen it explained that some conductors are non-ohmic because the temperature caused by the current changes the resistance in the circuit. If that’s the case, isn’t ohms law still being obeyed, just with a varying resistance.
6. ### I Improper integrals

if I wanted to take the definite integral of 1/x with respect to x, with the bounds -1 and 1, the integral would be improper. What about the indefinite integral? We can find the indefinite integral of 1/x to be ln|x|. Can we find the indefinite integral of discontinuous functions?
7. ### B Voltage drop over a resistor

Why is the electrical potential greater before it passes through a resistor than after?
8. ### B Current without voltage

in a circuit like the one in the attached picture, the voltage between two points in between two resistors should be 0. But there is current flowing through the circuit. So what’s going on here? Does ohms law not apply in this situation for some reason?
9. ### B Voltage in a series circuit

If I had a simple series circuit with only a single resistor, and I used a voltmeter to find the voltage between a point at the end of the circuit and another point, which was moved from the beginning to the end of the circuit, what would I find at these various point? Would the voltage remain...
10. ### I What Must Conductors be Made of

When we think of conductors in an abstract sense, charges can flow freely through them. What are these abstract conductors made of? I understand that conductors in the real world are made primarily of protons and electrons, But that it doesn’t seem like that is necesarrily the case. If we had...
11. ### B Representing Vectors

I recently had a test question where I had to calculate a force on a charged particles from two other charges particles. The answer ended up having an x and a y component. I realized I wasn’t quite sure how to represent that vector. Should I just have written it as something like 5Nx^ + 6Ny^...
12. ### I Dx as a small change in x

Can dx be thought of as a sufficiently small change in x? I want to say that dx is the change in x and change in x approaches 0, but that would just be 0. So I think it might make more sense to just say sufficiently small. Then when we look at something like a derivative dy/dx we can look at...
13. ### I Partial fractions

im a bit confused about partial fractions If we have something like x/((x+1)(x+2)) we could decompose it into a/(x+1) +b/(x+2) If we had something like x/(x+1)^2 we could decompose it into a/(x+1) + b/(x+1)^2 We use a different procedure when there is a square in part of the polynomial in...
14. ### I Conductors without real world particles

do conductors have to be thought of in terms of protons and electrons? We can think of charged objects as continuous charge distributions for example without reference to any sort of real world particles. This is much simpler to grasp for me. Is the same sort of thing done for conductors, or...
15. ### B Quotient limit law

The quotient limit laws says that the limit of a quotient is equal to the quotient of the limits. If we had a limit as x approaches 0 of 2x/x we can find the value of that limit to be 2 by canceling out the x’s. If we split it up we get the limit as x approaches 2 of 2x divided by the limit...
16. ### B Basic Graphing

it’s been a while since I’ve learned basic graphing in math. I feel like whenever I graph something, it’s sloppy and probably doesn’t follow the proper conventions. So what are the basics of graphing? You draw a line with arrows on each end for each axis. Should the axis always be labeled? Do...
17. ### I Gauss’ law and Enclosed Charges

What exactly does the electric field as solved for by Gauss’s law tell us? If you use a Gaussian surface that encloses no charge you find that the electric field is equal to 0. But if there is a charge outside of that Gaussian surface, it is not true that the electric field is 0 on the Gaussian...
18. ### I What is dx

Often I have to solve problems using dx or dq. I always don’t quite understand what’s going on. I understand what dy/dx is but not just dx. Can someone walk me through in plain language a somewhat rigorous definition of differential like dx?
19. ### I Electric potential and voltage in a circuit

As I understand it, electrical potential is the potential energy of a unit charge in some point in space. How does this idea relate to the idea of voltage in a circuit? The term electric potential seems to be used for both.
20. ### I Electric field inside a conductor

The electric field inside of a conductor is 0, but what exactly does inside a conductor mean? It’s easy enough to understand what this means if the conductor is closed, but what if the conductor is open in some way? What counts as inside and what doesn’t?
21. ### B Vectors and division

As far as I know, vectors can only be added, subtracted, or “multiplied” by dot or cross product. Does this mean that you couldn’t divide f-> by a-> to get m using the vector form of Newton’s second law? This would require dividing a vector by a vector, which seems to not be allowed.
22. ### Potential of hollow open ended cylinder

Homework Statement A hollow circular cylinder, of radius a and length b, with open ends, has a total charge Q uniformly distributed over its surface. What is the difference in potential between a point on the axis at one end and the midpoint of the axis? Show by sketching some field lines how...
23. ### Potential of charged cylinder

Homework Statement For the cylinder of uniform charge density in Fig. 2.26: (a) show that the expression there given for the field inside the cylinder follows from Gauss’s law; (b) find the potential φ as a function of r, both inside and outside the cylinder, taking φ = 0 at r = 0. 2...
24. ### Potential at the center of a sphere between two long rods

Homework Statement A spherical shell with radius R and surface charge density σ is sandwiched between two infinite sheets with surface charge den- sities −σ and σ , as shown in Fig. 2.46. If the potential far to the right at x = +∞ is taken to be zero, what is the potential at the center of...
25. ### B The shell theorem and particles

As two particles become closer to each other, the gravitational force (or electric force) approaches infinity. If this is the case, then how does the Shell theorem work? If two particles are extremely close together, there should be an extremely large force. If we then build a sphere around...
26. ### Extrema of electrical potential

Homework Statement A charge of 2 C is located at the origin. Two charges of −1 C each are located at the points (1, 1, 0) and (−1, 1, 0). If the potential φ is taken to be zero at infinity (as usual), then it is easy to see that φ is also zero at the point (0, 1, 0). It follows that somewhere...
27. ### Plotting Potential

Homework Statement Consider the system of two charges shown in Fig. 2.8. Let z be the coordinate along the line on which the two charges lie, with z = 0 at the location of the positive charge. Make a plot of the potential φ (or rather 4πε0φ, for simplicity) along this line, from z = −5 m to z...
28. ### I Gauss’s Law: What is E?

Gauss’s law is stated as follows What exactly does E describe. If you use a Gaussian cylinder for example, where does the value of E describe the electric field?
29. ### B Electric Field Line Strength

Supposedly the strength of the electric field is is related to the distance between electric field lines. I have two questions about what exactly this means. 1.) What is the distance between electric field lines? Is it just the distance between two points on adjacent electric field lines that...
30. ### I Gauss’ law and an infinite rod

To find the electric field from an infinitely long charged rod you can use gauss’s law with a cylinder as your Gaussian surface. I don’t quite understand by this works. Wouldn’t the electric field given by the equation only be the electric field cause by the charge within the cylinder? And if...