Q. A student yells across a street at a concrete wall. The student hears an echo 0.500 seconds later. If the speed of sound in air is 343 m/s, what is the distance from the student to the wall only?
Q. The electric field between plates of a parallel plate capacitor (similar to the ceiling and floor of charge we considered in Monday's class) is the charge density (charge per unit area on one of the plates) divided by epsilon-0, the so-called permittivity of free space, as given in Eq. 18.4. A parallel plate capacitor has a potential difference of 200 V between its plates, which are 0.50 mm apart.
a. What is the magnitude of the electric field between the plates?
b. What is the charge density on the plates?
c. If the plates have an area of 10.0 square centimeters, how much charge is on the positive plate?