physics please help me?

[oocowsoo]

1. A uniform electric field with a magnitude of 6610 N/C points in the positive x direction. Find the change in electric potential energy when a +12.5 µC charge is moved 5.60 cm in the following directions.
(a) the positive x direction
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(b) the negative x direction
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(c) the positive y direction
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2. A point charge of -7.2 µC is at the origin.
(a) What is the electric potential due to this charge at (2.5 m, 0)?
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(b) What is the electric potential to this charge at (-2.5 m, 0)?
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(c) What is the electric potential to this charge at (2.5 m, -2.5 m)?
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3. The Earth has an electric field with a magnitude of approximately 104 V/m near its surface. What is the potential difference between a point on the ground and a point on top the Ostankino Tower (1762 ft high)?
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please someone explain this step by step so i can understand how to get the answer