Apoint charge is placed at each corner of a square with side length a. the charges all have the same magnitude q. two of the charges are positive and two are negative, as shown in the following figure. q: what is the magnitude of the net electric field at the center of the square due to the four charges in terms of q and a?

Listed following are various physical situations that describe how light interacts with matter. match these to the appropriate category. 1) transmission? -visible light meets clear glass -visible light does not pass through a black wall -red light hits a red sweatshirt -light comes from your computer screen -cell phone signals pass through walls -blue light hits a red sweatshirt -white light hits a white piece of paper -light comes from a light bulb