What happens if an electron is near a proton? Find a simulation that allows you to get an electron to circle around the nucleus. (Refresh the page if it asks you to Subscribe) What does this resemble? What happens to force on the electron as it gets closer to the nucleus? Find a simulation in which you have two charged particles next to one another and where you can alter the charge on at least one of them. What happens to the net electric field as q2 approaches 0 C (neutral)? Use a series of three diagrams to show the changes. Draw the electric fields for the following: Single positive charge Single negative charge Two equal positive charges Two equal negative charges Equal unlike charges Unequal like charges Unequal unlike charges In a simulation that shows you electric field lines and allows you to alter the charge, what do you notice about the relationship between charge and electric field lines? Do field lines ever cross? Why? Score a "Goal" on Difficulty level 3 with this simulator and take a picture! Note: This simulator may take a minute or so to load. If stuck, refresh the tab.

Aheat engine running backward is called a refrigerator if its purpose is to extract heat from a cold reservoir. the same engine running backward is called a heat pump if its purpose is to exhaust warm air into the hot reservoir. heat pumps are widely used for home heating. you can think of a heat pump as a refrigerator that is cooling the already cold outdoors and, with its exhaust heat qh, warming the indoors. perhaps this seems a little silly, but consider the following. electricity can be directly used to heat a home by passing an electric current through a heating coil. this is a direct, 100% conversion of work to heat. that is, 19.0 \rm kw of electric power (generated by doing work at the rate 19.0 kj/s at the power plant) produces heat energy inside the home at a rate of 19.0 kj/s. suppose that the neighbor's home has a heat pump with a coefficient of performance of 4.00, a realistic value. note: with a refrigerator, "what you get" is heat removed. but with a heat pump, "what you get" is heat delivered. so the coefficient of performance of a heat pump is k=qh/win. an average price for electricity is about 40 mj per dollar. a furnace or heat pump will run typically 200 hours per month during the winter. what does one month's heating cost in the home with a 16.0 kw electric heater? what does one month's heating cost in the home of a neighbor who uses a heat pump to provide the same amount of heating?