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## Electrical potential problems

Hi guys I am learning about electrostatic on my own and was solving some problems but I am having problems with these questions please help.

An electron is released within a uniform electric field of a magnitude of 28,000 N/C generated by two parallel plates. The plates are separated by 4 cm. If the electron has moved across the entire gap between the plates, what is its speed?

We can get the force of the Particale in such electric field
which will be
F = 28 * 10^3 * - 1.6 * 10^-19;
F = -4.48 * 10^-15;

We know here it will follow a parabolic path so I have stopped from here I don't know where to start to solve this problem.

How much work is required to bring a 10.0 μC charge from infinity to 5.00 meters away from a point charge of -2.00 μC?

I solved this problem but can't find the answer on the given choices,since they don't provide answer here is how I tried to solve for it. I want to know if my answer is correct.

I reasoned through this as follows I assumed the charge is already 10 charge is 5 meters away,since the potential from infinity is zero and this would approximate result.
So I got the force that they were putting on each other distance 5 meters away as:

F = 9 * 10^9 * 10 * 10^-6 * -2 * 10^-6 / 5^2 = -7.2 * 10^-3;
So work done should be w = -7.2 * 10^-3 * 5 = -0.036J;
W = -3.6 * 10^-2

The answer exists in the multiple choice but I don't know if its correct please let me know if it is.

An electron moves 0.10 m along the direction of an electric field of a magnitude of 3.0 N/C. What is the potential difference between the electron’s initial and final points?

a. 4.8 x 10–20 V
b. 1.6 x 10–20 J
c. –4.8 x 10–20 J
d. –1.6 x 10–20 J

I don't know where to start to solve this problem.