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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How will the spheres be charged, if at all?

Rod2Spheresv3Two uncharged conducting spheres, A and B, are suspended from insulating threads so that they touch each other. While a positively charged rod is near A (not touching sphere A), the spheres are moved apart. How will the spheres be charged, if at all?

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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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How much heat is released ?

elBallA spherical conductor has a capacitance of 8 µF and it is charged to a potential of 2000V. The conductor is connected with a long thin wire to an another uncharged spherical conductor of capacity of 32 µF.
Determine how much heat is released.

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A spherical drop of water carrying a charge.


A spherical drop of water carrying a charge of 0.032 nC has a potential of 512 V at its surface.

a) What is the radius of the drop?
b) If two such drops with the same radius and charge were to combine to form a single drop, what would be the potential at the surface of the new drop?



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Cinderella’s challenge.

Cinderella Cinderella’s stepmother shook some salt onto a flat surface with a tablecloth and after shook some pepper over the salt. She mixed the salt and pepper together with her fingertips until there was an even mixture of pepper and salt. Cinderella must to separate the pepper from the salt without touching neither the one nor the other. What should Cinderella do?

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