In a cathode ray tube, electrons are accelerated fromrest by a constant electric
ID: 1680426 • Letter: I
Question
In a cathode ray tube, electrons are accelerated fromrest by a constant electric force of magnitude 6.45 x1017 N during the first 2.18 cm of tube's length;then they move at essentially constant velocity another 45.0 cmbefore hitting the screen. Find the speed of the electrons whenthey hit the screen. How long does it take them totravel the length of the tube?Explanation / Answer
gained in kinetic energy =work done by force=F*0.0218=1.41*10^-18J=1/2*m*v^2 =>v=1.76*106 m/s the speed of the electrons when they hit thescreen.=v=1.76*106m/s time to travel the length of the tube; t=0.0128*2/v=2.48*10^-8 s