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1.An electrical heater in a system for providing domestic hot water is rated at

ID: 1370268 • Letter: 1

Question

1.An electrical heater in a system for providing domestic hot water is rated at 5.0 kW of electric power if its input voltage is 120 V . (a) Find the resistance of the heater. (b) How long must the heater be on in order to bring 2.0 m3 of water from 20C to 50C, assuming that 90% of the electrical energy delivered to the heater is transformed into heat?

2.Three point charges are arranged as shown in the figure. The charges +Q and Q have the same magnitude of 3.0 µC. The positive charge at the origin has a magnitude of 5.0 µC. The distances are a = 0.40 m and b = 0.20 m. (a) Find the electrical field at the origin created by the charges +Q and Q. (b) Find the electric force exerted on the charge q by the charges +Q and Q. ( i had a hard time trying to upload the picture, but -Q is on the negative y-axis, +Q is on the positive x-axis and there is a +q on the origin)

3.Four charges are placed around the corners of a square as shown in the figure. The magnitude of q is 2.0 µC and the length of the side of the square is a = 0.10 m. (a) Find the electric potential due to the four charges at the center of the square. (b) Find the total electrostatic potential energy of the arrangement of four charges. ( i also could not upload a pic here either, but its bascially a square with four charges placed around its corners with -q charge on all the corners but the top right one; its +2q)

Explanation / Answer

1.An electrical heater in a system for providing domestic hot water is rated at