physics

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I have these problems that I keep doing and keep missing. If someone could please help me with what I am doing wrong!

Two charges, -25 µC and +15 µC, are fixed in place and separated by 3.4 m.
(a) At what spot along a line through the charges is the net electric field zero? Locate this spot relative to the positive charge. (Hint: The spot does not necessarily lie between the two charges.)
(b) What would be the force on a charge of +16 µC placed at this spot?

I did this a bunch of ways. One was saying E=kq/r.
So I got E=k(-25x10^-6)/x^2 + k(15x10^-6)/(3.4-x)^2 I had no idea where to go from there

Another way was (25)(x)^2 = 15(x-3.4)^2 From here I got the crazy answer of 4.164132563.

2. Two charges are placed between the plates of a parallel plate capacitor. One charge is +q1 and the other is q2 = +2.50 µC. The charge per unit area on each plate has a magnitude of σ = 2.00 10-4 C/m2. The force on q1 due to q2 equals the force on q1 due to the electric field of the parallel plate capacitor. What is the distance r between the two charges?

I used E=sigma/Eo which was 2x10^-4/8.85x10^-12. This came to 2.2598870.06
Then I did F=qE and F=kq1q2/r^2.

I set this = to each other with the q’s cancelling out and got 100. Which is wrong.

• physics -

1. one charge negative, one charge positive. You wont get a solution in between the charges, because the E is in the SAME direction, they are not in opposite direction, so they will never cancel.
So, the position of x is outside the charges. Let x be the distance from one, 3.4+x be the other distance.

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I think I'm using the wrong formulas or SOMETHING... Here's the question: "Two equal charges are separated by 3.7 ´ 10^-10 m. The force between the charges has a magnitude of 2.37 ´ 10^-3 N. What is the magnitude of q on the charges?
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Two charges, -17 and +3.6 µC, are fixed in place and separated by 3.2 m. (a) At what spot along a line through the charges is the net electric field zero?
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The text passage contains two physics problems related to electric fields and forces between charges. The problems are described but not fully solved, and no answers are provided.
multiple_questions
Given a text passage, determine:
    1. If it contains a mathematical question (including word problems or calculations)
    2. If an answer to that mathematical question is provided in the text

First, describe the content structure you found in 1-2 sentences.

Then provide your analysis in the following format:
TYPE: <one of the following values>
- NO_QUESTION
- SINGLE_QUESTION
- SINGLE_QUESTION_WITH_ANSWER
- MULTIPLE_QUESTIONS
- MULTIPLE_QUESTIONS_WITH_ANSWERS
system
physics

posted by .

I have these problems that I keep doing and keep missing. If someone could please help me with what I am doing wrong!

Two charges, -25 µC and +15 µC, are fixed in place and separated by 3.4 m.
(a) At what spot along a line through the charges is the net electric field zero? Locate this spot relative to the positive charge. (Hint: The spot does not necessarily lie between the two charges.)
(b) What would be the force on a charge of +16 µC placed at this spot?

I did this a bunch of ways. One was saying E=kq/r.
So I got E=k(-25x10^-6)/x^2 + k(15x10^-6)/(3.4-x)^2 I had no idea where to go from there

Another way was (25)(x)^2 = 15(x-3.4)^2 From here I got the crazy answer of 4.164132563.

2. Two charges are placed between the plates of a parallel plate capacitor. One charge is +q1 and the other is q2 = +2.50 µC. The charge per unit area on each plate has a magnitude of σ = 2.00 10-4 C/m2. The force on q1 due to q2 equals the force on q1 due to the electric field of the parallel plate capacitor. What is the distance r between the two charges?

I used E=sigma/Eo which was 2x10^-4/8.85x10^-12. This came to 2.2598870.06
Then I did F=qE and F=kq1q2/r^2.

I set this = to each other with the q’s cancelling out and got 100. Which is wrong.

• physics -

1. one charge negative, one charge positive. You wont get a solution in between the charges, because the E is in the SAME direction, they are not in opposite direction, so they will never cancel.
So, the position of x is outside the charges. Let x be the distance from one, 3.4+x be the other distance.

Similar Questions

1. physics

Two charges, -37 µC and +3 µC, are fixed in place and separated by 2.8 m. (a) At what spot along a line through the charges is the net electric field zero?
2. Math Urgent

1 )3x + 8y = 1 7x + 4y = 17 Answer: (3,1) 2) -3x + 5y = -7 9x + 2y = 38 Answer: (4,1) 3) 7r + 3s = 13 14r - 15s = -16 Answer: (1,2) 4) 2x - 7y = 42 4x - 14y = 64 Answer: No Solution ?
4. Physics (SO CONFUSED!!!)

I think I'm using the wrong formulas or SOMETHING... Here's the question: "Two equal charges are separated by 3.7 ´ 10^-10 m. The force between the charges has a magnitude of 2.37 ´ 10^-3 N. What is the magnitude of q on the charges?
5. physics 2

1) A spherical surface completely surrounds a collection of charges. Find the electric flux through the surface if the collection consists of a single +3.93E-6 C charge. 2) A plate carries a charge of -2.52μC, while a rod carries …
6. Physics

Two charges, -15 and +4.5 µC, are fixed in place and separated by 2.8 m. At what spot along a line through the charges is the net electric field zero?
7. physics 2

Two charges, -17 and +3.6 µC, are fixed in place and separated by 3.2 m. (a) At what spot along a line through the charges is the net electric field zero?
8. physics

Two charges, -17 and +3.6 µC, are fixed in place and separated by 3.2 m. a) At what spot along a line through the charges is the net electric field zero?
9. Physics

A charge of -3.66C is fixed at the center of a compass. Two additional charges are fixed on the circle of the compass (radius = 0.0978 m). The charges on the circle are -4.04C at the position due north and +6.20C at the position due …
10. Chemistry

Two fixed charges, -4μC and -5μC, are separated by a certain distance. If the charges are separated by 20cm, what is the magnitude of the electric field halfway between the charges?

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user
The text passage contains two physics problems related to electric fields and forces between charges. The problems are described but not fully solved, and no answers are provided.

TYPE: MULTIPLE_QUESTIONS