An Empire starship fires at Skywalker’s ship


An Empire starship fires a beam of electrons at Skywalker’s ship. Each electron has an initial kinetic energy of 1.6×10−17 J. The Skywalker’s ship has been fitted out with the electrostatic shield technology for defense against electron beam weapons. The electric field of the shield points directly inward. If the electrons stop after travelling 83 m, what is the size of the electric field generated by the ship’s shield? Please ignore relativistic effects.

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Two spheres with electric charges

MARBLES2Two geometrically identical spheres with electric charges Q and 3Q are separated by a distance of r in a vacuum. The electrostatic force between them is 48 µN. The two spheres are brought into contact and then separated to the former distance. Determine the magnitude of the force that each sphere now experiences.

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