The current in an electron beam in a cathode ray tube is 7.0 X 10^-5 A. A beam of electrons is aimed at a screen. How much charge hits the screen in 5.0S?
The current I is defined as the quantity of charge Q that flows in the tube in the unit of time t: [tex]I = \frac{Q}{t} [/tex] In our problem, we have [tex]I=7\cdot 10^{-5} A[/tex] and the time is t=5.0 s. Therefore we can find the charge that hits the screen during this time: [tex]Q=It =7\cdot 10^{-5} A \cdot 5.0 s=3.5X10^{-4} C[/tex]
