E, FDAC Solving E-Field with Charges

[n77ler]

[SOLVED] E-field with charges

I've tried this 8 times and have 2 tries left, Looking for some hints

Homework Statement

The figure shows the E-field in the plane of two point charges. (Give ALL correct answers, i.e., B, AC, BCD...)
A) Q1 is positive.
B) A - charge placed at `a' would move left.
C) Q1 and Q2 have the same sign.
D) A + charge at `a' would move left.
E) The magnitude of E is the same at `a' and `b'.
F) |Q1| is larger than|Q2|

Homework Equations

The Attempt at a Solution

FAB, FABE, FAD, FADE ,FDA

 

[n77ler]

noone? :(

 

[Hootenanny]

Sorry n77ler, I didn't notice your post! Okay, how about you state whether each statement is true or false and give your reasons and we'll take it from there?

I can't promise that I'll get back to you tonight as it's pretty late here, but I'm sure someone else will jump in. If not I'll check in again tomorrow

 

[n77ler]

OK so for A I think it is true because direction of field is supposed to travel away from a positive charge, and Q1 has arrows pointing away from it.

B: a negative charge here, I think it would move left? But I am not sure about this one

C: False because arrows are going in opposite directions towards each point Q2 is negative and Q1 is positive i think.

D: I think this is true but I am not positive about it

E: I think false. I don't think they can be the same magnitude of E because the radius is different for each one isn't it?

F: True. If e field lines are more dense around a point it means that it has a higher charge or maghnitude of e

 

[Hootenanny]

OK so for A I think it is true because direction of field is supposed to travel away from a positive charge, and Q1 has arrows pointing away from it.

Correct

B: a negative charge here, I think it would move left? But I am not sure about this one

In which direction do electric field lines point? Think about how the electric field vector is defined. (see you answer below)

C: False because arrows are going in opposite directions towards each point Q2 is negative and Q1 is positive i think.

Correct.

D: I think this is true but I am not positive about it

Correct

E: I think false. I don't think they can be the same magnitude of E because the radius is different for each one isn't it?

It is indeed false, but for the wrong reasons. What does the density of the electric field lines tell you about the strength of the electric field (see your point below).

F: True. If e field lines are more dense around a point it means that it has a higher charge or magnitude of e

Correct.

 

[n77ler]

Electric fields point negative don't they?

 

[Hootenanny]

Electric fields point negative don't they?

They point from positive charges to negative charges or in the direction in which a positive test charge would move.

 

[n77ler]

ok so the negative charge would move to the right making it false

 

[n77ler]

so the answer includes all the true statements: ADF

 

[Hootenanny]

so the answer includes all the true statements: ADF

Yes, I would go with that

 

[n77ler]

good stuff, now I have the right answer and understand :) thanks!

 

[Hootenanny]

good stuff, now I have the right answer and understand :) thanks!

No worries