Find the Y component of Electric field at a point

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SUMMARY

The discussion focuses on calculating the electric field's Y component at point P due to a charged vertical rod with length L = 5.0 cm and total charge Q = 3.0 nC. The initial attempts yielded incorrect results due to misunderstanding the charge distribution and the need for integration. The correct approach involves using linear charge density and integral calculus to derive the electric field components accurately. The final correct answer for the Y component was determined to be approximately -8700 N/C after proper integration.

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  • #31
I just did the integration and got -140677.0588 and that was incorrect.
I had my integral limits from 0 to 0.05 and ∫(kqy(dy)/(a(x^2+y^2)3/2))

used U substitution and was a pretty straight forward integral. not sure what I did wrong here
 
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  • #32
isukatphysics69 said:
I just did the integration and got -140677.0588 and that was incorrect.
I had my integral limits from 0 to 0.05 and ∫(kqy(dy)/(a(x^2+y^2)3/2))

used U substitution and was a pretty straight forward integral. not sure what I did wrong here
It's much more helpful to do the integration using symbols. Plug in the numerical values later. There is virtually no way for anyone to look at the result, −140677.0588 and tell what might be wrong with it. It doesn't even have units.

That is pretty close to being the correct integral.
Having ##\ q\ ## there isn't correct. That should be ##\ \lambda\ ##, the linear charge density.
What is ' a ' ? (It's in the denominator.)
For integration limits, 0 to L .​

What do you get for the integral, prior to substituting the integration limits?.
 
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  • #33
SammyS said:
It's much more helpful to do the integration using symbols. Plug in the numerical values later. There is virtually no way for anyone to look at the result, −140677.0588 and tell what might be wrong with it. It doesn't even have units.

That is pretty close to being the correct integral.
Having ##\ q\ ## there isn't correct. That should be ##\ \lambda\ ##, the linear charge density.
What is ' a ' ? (It's in the denominator.)
For integration limits, 0 to L .​

What do you get for the integral, prior to substituting the integration limits?.
I had 'a' as the length of the entire rod, I will try again
 
  • #34
This is really frustrating but I am staying calm like a monk
 
  • #35
isukatphysics69 said:
I had 'a' as the length of the entire rod, I will try again
Well in that case, that does give you a factor of q/L, which is correct and it's needed because, q/L is λ .

Making that replacement, makes your integral:
∫(kqy(dy)/(L(x2+y2)3/2)) with limits from 0 to L .

In more readable form, using LaTeX that can be written:
##\displaystyle \frac{kq}{L} \int_0^L \frac {y\,dy}{(x^2+y^2)^{3/2}} \,,\ ## where I factored out the constant factors.​
.
 
  • #36
ok I got the answer it is -8700 rounded with sig figs. Thank you @haruspex @SammyS. now I will attempt the x component since I got lucky with that one
 

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