A sphere is charged to 20 µC. Find the potential at the following points. A, B and C (A point is at the center of the sphere, B is at the surface and C is 4cm from the surface.) AB r1=2cm, BC r2=4cm
You drop a rock into a well and count the seconds before you hear a splash. If you counted 10 seconds before you heard the splash, how deep is the well?