The electron beam in a cathode-ray tube is accelerated through apotential difference of 290 V. The electrons then pass through a small circularhole and are viewed on the screen. You observe that the centralbright spot on the screen is the base of a cone with its apex atthe hole. The outer edge of the cone makesa 0.860 ^\circangle with the original direction ofthe electron beam.
a.) What is the diameter of the hole?