4. A thin rod of length ℓ and uniform charge per unit length λ lies along the x axis, as shown in the Figure. (a) Show that the electric field at P, a distance y from the rod along its perpendicular bisector, has no x component and is given by E = 2ke λ sin θ0/y. (b) What If? Using your result to part (a), show that the field of a rod of infinite length is E = 2ke λ /y. (Suggestion: First calculate the field at P due to an element of length dx, which has a charge λ dx. Then change variables from x to θ, using the relationships x = y tan θ and dx = y sec2 θ dθ , and integrate over θ.)(adsbygoogle = window.adsbygoogle || []).push({});

for this problem, im not gettin how u arrive at the E field. (ie part a)

the other problem:

7. A line of charge with uniform density 35.0 nC/m lies along the line y = 15.0 cm, between the points with coordinates x = 0 and x = 40.0 cm. Find the electric field it creates at the origin.

i get the value but not the irection of the E field.

can u please help me out

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# Two problems gettin on my nerve

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