Electric Fields: Help Needed for Questions on Charge and Magnitude

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The discussion focuses on questions related to calculating electric fields and charge distributions. Participants seek assistance with three specific problems involving excess electrons on a spherical conductor, the net electric field from two parallel lines of charge, and determining the charge in a section of a line of charge. Key equations mentioned include E = λ / (2πε₀r) for electric fields due to line charges. The user is looking for guidance on the relevant equations and concepts rather than direct answers to the problems. Understanding the relationship between charge distributions and electric fields is central to solving these questions.
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help needed on a couple questions - electric fields

anyone able to lend a hand?

1. How many excess electrons must be added to an isolated spherical conductor of diameer 30.0 cm to produce an electric field of 1155 N/C just outside the surface?

permittivity of free space and charge on an electron are given

2. A very long uniform line of charge has charge per unit length 4.62 \mu C/m and lies along the x-axis. A second long uniform line of charge has charge per unit length -2.46 \mu C/m and is parallel to the x-axis at y_1 = 0.414 m.

What is the magnitude of the net electric field at point y_2 = 0.188 m on the y-axis?

for this one i think it's along the lines of E = lamda/ 2 pi ep_0 r, but I'm not sure of which values are to be used


and...

3. The electric field at a distance 0.485 m from a very long uniform line of charge is 880 N/C.
How much charge is contained in a section of the line of length 2.00 cm?

i don't want the answer but help on how to solve the questions
 
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What equations relate charge distributions to electric field?
 
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