Are electronic listening devices(bugs)detectors available for purchase?
Are electronic listening devices(bugs)detectors available for purchase?
How far should the front of the camera be from her friend?
How far should the front of the camera be from her friend?
A student has built a 17–long pinhole camera for a science fair project. She wants to photograph her 160–tall friend and have the image on the film be 4.9 high.