Practice: Draw the field lines for a pair of identical, negative charges.

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Coulomb's Law (Electric Force) | 48 mins | 0 completed | Learn Summary |

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Electric Fields in Capacitors | 14 mins | 0 completed | Learn |

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Practice: Draw the field lines for a pair of identical, negative charges.

Example #1: Field Lines of Electric Quadrupole

**Transcript**

Hey guys. Let's do another example of drawing electric field lines, okay? Draw the electric field lines for the four Chargers shown below this arrangement is known as an electric quadripole, okay? So, just like we had an electric dipole which was two charges, di 2, we have an electric quadripole, Quadra being four, charges arranged like shown, okay? The important thing to remember here is that the electric field decreases pretty rapidly with distance, okay? The electric field is what we call directly proportional to 1 over r squared that means that, when r doubles that two is actually squared. So, E becomes one over four, when r triples he becomes one over nine. So, it's not just that it drops off linearly it drops off very, very rapidly like this, this is the electric field versus r, basically what I'm getting at is that only nearby charges affect the electric field lines. So, we can do is we can actually look at this as a collection of multiple dipoles and our electric field lines are going to look like that, okay? So, let's start.

These dipole lines are going to go from the negative, sorry, from the positive to the negative, is the other direction, okay? These dipole lines are going to go from the positive to the negative, these dipole lines are going to go from the positive to the negative and these dipole lines are going to go from the positive to the negative with very, very little influence. Now, the closer we get to the center the more it looks like a dipole, sorry, the less it looks like a dipole the more we get away from the center the more it looks like a dipole, so the further away this actually looks even more like a dipole the further away this looks even more like a dipole this one looks even more like a dipole, okay? Now, what happens as we get near the center? Well, at the very center we have an electric field down due to the top positive charge, we have an electric field up due to the bottom positive charge, we have an electric field to the left due to the right negative charge, sorry, 2 to the left negative charge and we have an electric field due to the right, to the right, due to the right negative charge, okay? Because all these charges are the same and because we're looking at the direct center so they're all the same distance from the center, we know that all of these electric fields cancel so the electric field is just going to be 0 at the center of the dipole, sorry, it's a quadrupole, okay? So, this is what it looks like, it looks like a collection of dipoles with a 0 electric field at the center.

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The Figure below shows electric field lines arising from two small charged particles P and Q.

Consider the electric field lines associated with the electric dipole below. Of the points shown, where does the electric field have the greatest magnitude?A) AB) BC) CD) D

Consider a pair of point charges ±Q , fixed in place near one another as shown. On the diagram below, sketch the field created by these two point charges.

The electric field lines are shown for a system of two point charges. Which of the following could represent the magnitudes and signs of QA and QB? In the following, take q to be a positive quantity.
a) QA = +q, QB = −q
b) QA = +7q, QB = −3q
c) QA = +3q, QB = −7q
d) QA = −3q, QB = +7q B
e) QA = −7q, QB = +3q

Four charges are arranged at the corners of a square, as depicted in the figure.(a) Using the symmetry of the arrangement, determine the direction of the electric field at the center of the square due to the four charges at the corners, given that qa = qb = -3.4 μC and qc = qd = 3.4 μC. Multiple Choice:1) Out of the screen2) Down 3) Right 4) Left5) Into the screen6) Up(b) Calculate the magnitude of the electric field, in newtons per coulomb, at the center of the square (the location of q), given that the square is 5.5 cm on a side. Numeric: A numeric value is expected and not an expression.I|E| = _________

Fig. 15-8 shows electric field lines near two electric point charges. If Q1 = -1 μC, what is the value of Q2? A) -1 μC B) 0C) +1 μC D) -2 μCE) +2 μC

A negative charge if free will tend to move: from low potential to high potentialCan you give a brief explanation why did we choose this answer?

The total positive charge is Q = 1.62 × 10-6 C.What is the direction of the electric field at point P? (Figure 2)Enter the letter of the vector that represents the direction of EP?

An electron is released from rest at point B (as shown to the right), where the potential is 0 V. Afterward, the electron: a. remains at rest at B.b. moves toward A with a steady speed. c. moves toward A with an increasing speed. d. moves toward C with a steady speed. e. moves toward C with an increasing speed.

Which of the following statements are true for electric field lines? (Select all that apply.) a. Electric field lines are close together in regions of space where the magnitude the electric field is strong and are father apart where it is weak. b. Electric field lines can never intersect. c. At every point in space, the electric field vector at that point is tangent to the electric field line through that point d. Electric field lines are close together in regions of space where the magnitude the electric field is weak and are father apart where it is strong. e. Electric field lines point away from positive charges and toward negative charges. f. Electric field lines are continuous; they do not have a beginning or an ending. g. At every point in space, the electric field vector at that point is perpendicular to the electric field line through that point.

Rank in order, from largest to smallest, the electric field strengths E1 to E4 at points 1 to 4 in the figure(Figure 1) . Please explain why

A semicircle of radius a is in the first and second quadrants, with the center of curvature at the origin. Positive charge +Q is distributed around the left half of the semicircle (0 to 90 degrees) and negative charge -Q is distributed uniformly around the right half of the semicircle (90 to 180 degrees).Part A: What is the magnitude of the net electric field at the origin produced by this distribution of charge?Express your answer in terms of variables Q, a, and appropriate constants.Part B: what is the direction of the net electric field at the origin produced by the distribution of this charge?+X direction, -X direction, +Y direction, or -Y direction

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