PHYSICS 1251 Lecture Notes - Lecture 6: Field Line, Electric Field, Gaussian Surface

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mauvegoldfish544

18 Jan 2019

School

Ohio State University

Department

Physics

Course

PHYSICS 1251

Professor

Tin-Lun Ho

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PHYSICS 1251 Lecture 4: Discrete Vs. Continuous Charges

PHYSICS 1251 Lecture Notes - Lecture 6: Field Line, Electric Field, Gaussian Surface

PHYSICS 1251 Lecture 7: Lecture Note Jan 22, 2019

Document Summary

F is unit from q to rector a q a in farther the points are from each other, the s the force. Closer the points are from each other, the greater the force. E electric eld lines point away from positive charge and towards negative charge whatiftwoalikechargesghareafieldi. Q"t given the eld lines going toward each other will repel causing the curving lines (in the center above) Q t the lines will bend to point towards the negative charge ma of fgravity f c remains in midair the electric field. Electricity add electric eld lines penetrate perpendicular to a surface of area a the number of lines per unit area (line density) is proportional to the magnitude of the electric eld. More lines, greater magnitude the product of the electric eld and the surface area is called the electric ux. toes e a. Neena the electric ux has the following units: the electric ux is proportional to the number of electric.

Related Questions

I am studying for a physics exam next Monday and I need tounderstand this concept a hell of lot better than I do. Hopefullysomeone on here can dumb it down for me.

My textbook says the following:

1. If the probe charge q is positive, the electric fieldvector points in the same direction as the force on the charge; ifnegative, the electric field vector points opposite theforce.

What is this really saying? I don't understand.

2. For the equation, Electric field = K|q|/r^2 , theelectric field is going away from q if q>0, and the electricfield is going toward q if q<0.

I don't understand this either. Is the electric field going awayfrom q because the electric field is negative and q is positive,thus q is attracted to the field? If q is negative then the fieldis going to be going toward q because it's being repelled from thenegative field?

I just want tounderstand the two bolded concepts above and how they relate toeach other, if they in fact do. My job does a horrible job atexplaining it.

Thanks.

1.Two uncharged, conducting spheres, A and B, are held at rest oninsulating stands and are in contact. A positively charged rod isbrought near sphere A. While the rod is in place, the two spheresare separated. How will the spheres be charged, if at all, afterthey are separated?
Sphere A Sphere B
(a) positive positive
(b) positive negative
(c) negative positive
(d) negative negative
(e) zero zero

2. A charged conductor is brought near an uncharged insulator.Which one of the following statements is true?
(a) Both objects will repel each other.
(b) Both objects will attract each other.
(c) Neither object exerts an electrical force on the other.
(d) The objects will repel each other only if the conductor has anegative charge.
(e) The objects will attract each other only if the conductor has apositive charge.

3. An electron is moved from point A, where the electric potentialis VA = â240 V, to point B, where the electric potential is VB =â360 V. What is the change in the electric
potential energy?
(a) 1.92Ã10â17 J (b) 2.04Ã10â17 J (c) 5.75Ã10â17 J (d) 8.98Ã10â17 J(e) 1.05Ã10â16 J

4. A -2q charge is located a distance d to the right of a +4qcharge, along the x
axis. At which point (or points) along the axis does the electricfield go to zero? To
solve this problem, consider an observer at point P, which is anarbitrary distance x from the +4q charge. Find the value (orvalues) for x (in terms of the separation distance d) where thetotal electric field vanishes.
(a) The electric field is never zero in the vicinity of thesecharges.
(b) The electric field is zero at x = -0.328d.
(c) The electric field is zero at x = +4.22d.
(d) The electric field is zero at both x = -2.26d and x =+2.26d.
(e) The electric field is zero at x = +3.41d.

5. point A is a distance L away from a point charge Q. Point B is adistance 4L away from Q. What is the ratio of the electrostaticpotential at B to that at A, i.e., what is VB/VA?
(a) 1/16
(b) 1/9
(c) 1/4
(d) 1/3
(e) can not be determined without specifying Q and L

6. Which one of the following statements best explains why it ispossible to define an electric potential
in a region of space that contains an electric field?
(a) Work must be done to bring two positive charges closertogether.
(b) Like charges repel one another and unlike charges attract oneanother.
(c) A positive charge will gain kinetic energy as it approaches anegative charge.
(d) The work required to bring two charges together is independentof the path taken.
(e) A negative charge will gain kinetic energy as it moves awayfrom another negative charge.