# physics help

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#1
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6 months ago
#2
... What do you need help with
You're kidding yourself if you think we're just gonna do all the work for you and spit out the answers.
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#3
(Original post by Slx.24)
... What do you need help with
You're kidding yourself if you think we're just gonna do all the work for you and spit out the answers.
Sorry I am not sure what they mean by taking into account of initial acceleration and how electrostatic repulsion varies with a proton and an electron. I attempted to see if the field lines were repulsive but it doesn't make sense.
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#4
I am also unsure of what will happen to the electron if it moves through the field. Does it have something to do with electrons having a very small mass therefore a very small change in the force experienced...
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6 months ago
#5
(Original post by dwrfwrw)
Sorry I am not sure what they mean by taking into account of initial acceleration and how electrostatic repulsion varies with a proton and an electron. I attempted to see if the field lines were repulsive but it doesn't make sense.
I assume that you are referring to (b)(ii).
How do you deduce electrostatic repulsion?
What do you mean by the field lines are repulsive? Where do you learn such concept?
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6 months ago
#6
(Original post by dwrfwrw)
I am also unsure of what will happen to the electron if it moves through the field. Does it have something to do with electrons having a very small mass therefore a very small change in the force experienced...
As for this, I assume you are referring to (b)(iii).
Note that in (b) the electric field is non-uniform, so the electric field strength at different positions is different and this implies that electric forces acting on the charge are different at different positions.
The separation of electric field lines can tell you the magnitude of the electric field strength.
Is the electric field strength increasing from left to right or right to left?
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#7
(Original post by Eimmanuel)
I assume that you are referring to (b)(ii).
How do you deduce electrostatic repulsion?
What do you mean by the field lines are repulsive? Where do you learn such concept?
What do you mean by the separation of the field lines? I mean isn't the electric field strength increasing from left to right since the field lines are more stronger which shows the direction of the force?
I'm not sure if the force is going to be going in the opposite direction or not?
Should electrons go in opposite directions to a proton since an electron is negatively charged?
If it is positive(proton), should it be going in the same direction as the field strength? I'm not exactly sure on this. Thank you though.
Last edited by dwrfwrw; 6 months ago
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6 months ago
#8
(i) You should be good with this one.
(ii) F = EQ. E is the same in a uniform electric field. Compare the charges of an electron and proton.
(i)F = EQ again. They are oppositely charged, so...
(ii)a = f/m. Mass of electron is smaller than a proton, so...
(iii) As the charges move, what happens to the field lines? Do they get closer or further apart? It's a radial field.
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#9
(i) You should be good with this one.
(ii) F = EQ. E is the same in a uniform electric field. Compare the charges of an electron and proton.
(i)F = EQ again. They are oppositely charged, so...
(ii)a = f/m. Mass of electron is smaller than a proton, so...
(iii) As the charges move, what happens to the field lines? Do they get closer or further apart? It's a radial field.
i, Would the force just be parallel to the direction to the field lines so towards the right then?
I know that the charge of a proton is 1.6x10 to power -19
charge of electron = -1.6x10to power -19
so wouldn't the force of an electron go in the opposite direction to the proton in the same non-uniform field?
interesting, why is g and A similar? Newton's 2nd law? A represents acceleration due to gravity right?
ii, Smaller mass= faster acceleration for the same magnitude of force for the electron compared to a proton which will have a lower acceleration
iii, As the charges move wouldn't the field lines just get closer together so wouldn't the force that's acting on the charges therefore increase? F proportional to 1/r squared, therefore if the charges would
Wouldn't iii involve the formula for electric field strength=(8.99x10 to 9) x (Q)/r squared
field strength is proportional to 1/r squared
so if the distance of the charges increase wouldn't the field strength increase therefore showing that
the force would also increase as F= electric field strength x charge where F and field strength are proportional to each other
Last edited by dwrfwrw; 6 months ago
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6 months ago
#10
(Original post by dwrfwrw)
What do you mean by the separation of the field lines? I mean isn't the electric field strength increasing from left to right since the field lines are more stronger which shows the direction of the force?
I'm not sure if the force is going to be going in the opposite direction or not?
Should electrons go in opposite directions to a proton since an electron is negatively charged?
If it is positive(proton), should it be going in the same direction as the field strength? I'm not exactly sure on this. Thank you though.
Before answering your questions, I would recommend that you read more better-word physics texts to appreciate the use of the physics terms and terminologies.

(Original post by dwrfwrw)
What do you mean by the separation of the field lines?
Separation of field lines is the distance between electric field lines or the spacing between electric field lines, so is just the separation of field lines.

(Original post by dwrfwrw)
I mean isn't the electric field strength increasing from left to right since the field lines are more stronger which shows the direction of the force?
What are you replying based on “I mean isn't the…”?
In Fig 2a and 2b, the separation of field lines becomes closer or the spacing of the lines becomes closer in going from left to right, implying that the electric field strength is becoming stronger in moving from left to right.
The reasoning of “field lines are more stronger” does not make sense in physics. Field lines are imaginary lines and it makes no sense of saying that they become stronger or weaker.
The direction of the electric force acting on a stationary positive test charge is given by the direction of the electric field lines NOT because “field lines are more stronger”.

(Original post by dwrfwrw)
I'm not sure if the force is going to be going in the opposite direction or not?
I am not sure which question are you replying to.

(Original post by dwrfwrw)
Should electrons go in opposite directions to a proton since an electron is negatively charged? If it is positive(proton), should it be going in the same direction as the field strength? I'm not exactly sure on this. Thank you though.
As mentioned above, the direction of the electric field line is that of the electric force on a stationary positive test charge placed in the field. So the direction of the electric force acting on the electron is opposite to the direction of the electric field lines because the electron is negatively charged.

https://openstax.org/books/universit...ic-field-lines
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6 months ago
#11
(Original post by dwrfwrw)
i, Would the force just be parallel to the direction to the field lines so towards the right then?

I know that the charge of a proton is 1.6×10-19

charge of electron = -1.6×10-19

so wouldn't the force of an electron go in the opposite direction to the proton in the same non-uniform field?
Assume that you are referring part (b)(i), your reasoning seems to be good.

(Original post by dwrfwrw)
interesting, why is g and A similar? Newton's 2nd law? A represents acceleration due to gravity right?
Not sure why are you connecting acceleration due to gravity g to this question.

(Original post by dwrfwrw)
ii, Smaller mass= faster acceleration for the same magnitude of force for the electron compared to a proton which will have a lower acceleration
Yes.

(Original post by dwrfwrw)
iii, As the charges move wouldn't the field lines just get closer together so wouldn't the force that's acting on the charges therefore increase? F proportional to 1/r2, therefore if the charges would
Wouldn't iii involve the formula for electric field strength=(8.99x10 to 9) x (Q)/r2
field strength is proportional to 1/r2
so if the distance of the charges increase wouldn't the field strength increase therefore showing that
the force would also increase as F= electric field strength x charge where F and field strength are proportional to each other
(b)(iii) does not require you to know the explicit electric field strength formula of the given electric field in Fig 2a and 2b.

It just requires a = Eq/m for you to make the correct explanation.

“As the charges move wouldn't the field lines just get closer together so wouldn't the force that's acting on the charges therefore increase?”

Which charged particles are you referring to?

I recommend that you re-read your statement in future and especially this quoted statement. This statement has the implication that the charged particle moves to “cause” the field lines to get closer.
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#12
(Original post by Eimmanuel)
Assume that you are referring part (b)(i), your reasoning seems to be good.

Not sure why are you connecting acceleration due to gravity g to this question.

Yes.

(b)(iii) does not require you to know the explicit electric field strength formula of the given electric field in Fig 2a and 2b.

It just requires a = Eq/m for you to make the correct explanation.

“As the charges move wouldn't the field lines just get closer together so wouldn't the force that's acting on the charges therefore increase?”

Which charged particles are you referring to?

I recommend that you re-read your statement in future and especially this quoted statement. This statement has the implication that the charged particle moves to “cause” the field lines to get closer.
Sorry sir I understood how you got the equation for biii but I'm not really sure how to approach this question still.
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#13
(Original post by dwrfwrw)
Sorry sir I understood how you got the equation for biii but I'm not really sure how to approach this question still.
(Original post by Eimmanuel)
Assume that you are referring part (b)(i), your reasoning seems to be good.

Not sure why are you connecting acceleration due to gravity g to this question.

Yes.

(b)(iii) does not require you to know the explicit electric field strength formula of the given electric field in Fig 2a and 2b.

It just requires a = Eq/m for you to make the correct explanation.

“As the charges move wouldn't the field lines just get closer together so wouldn't the force that's acting on the charges therefore increase?”

Which charged particles are you referring to?

I recommend that you re-read your statement in future and especially this quoted statement. This statement has the implication that the charged particle moves to “cause” the field lines to get closer.
So the diagram shows field strength getting stronger from left to right as the object moves initially from left to right, therefore as the object moves from left to right this will cause the force acting on the protons and electrons to be more stronger as a result. This will cause the acceleration of the electron to be higher than the acceleration of the proton? F/m=a
lower m=greater acceleration for electron compared to proton?
I seem to be confusing myself..
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6 months ago
#14
(Original post by dwrfwrw)
So the diagram shows field strength getting stronger from left to right as the object moves initially from left to right, therefore as the object moves from left to right this will cause the force acting on the protons and electrons to be more stronger as a result. This will cause the acceleration of the electron to be higher than the acceleration of the proton? F/m=a

lower m=greater acceleration for electron compared to proton?

I seem to be confusing myself.
I can “see” the confusion.
Note that your “reasoning” from the following statement is not entirely correct.

“So the diagram shows field strength getting stronger from left to right as the object moves initially from left to right, therefore as the object moves from left to right this will cause the force acting on the protons and electrons to be more stronger as a result.”

Avoid writing such long sentences if you are not good at writing such sentences. This is often the source of confusion and problem in exams.

Analyze the situation on proton first and apply the same analysis to the electron.

1) Is the proton moving to the right or left?
2) Does the magnitude of the electric field strength increase or decrease when the proton moves to a new position?
3) Apply a = qE/mp to the proton when it is in a new position.

Do the same analysis for the electron.
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