Athin, horizontal square copper plate has a length of 6.35cm and is charged with 2.56 × 108 electrons. if the electrons are uniformly distributed on the surface, calculate the value of the electric field (with the upward direction positive).
why is the strength of the electric field at the plate's centre of mass?

I'm thinking it's 2 you are asked to explain the earth's magnetic field. which is the best reply? 1. the earth's magnetic south is similar to the north pole of a magnet. 2. the earth's core has a strong magnetic charge similar to the south pole of a magnet. 3. the earth's geomagnetic south is similar to the south pole of a magnet. 4. the earth's magnetic charge is not centered at either pole; it varies based on location.

Achlorine atom has 17 protons and 18 neutrons. what is its mass number? what is its atomic number?

6–43 a food department is kept at 2128c by a refrigerator in an environment at 308c. the total heat gain to the food department is estimated to be 3300 kj/h and the heat rejection in the condenser is 4800 kj/h. determine the power input to the compressor, in kw and the cop of the refrigerator.