77. Two electrons are 109 m apart when they are
released. What is their speed when they are
108 m apart?
78. How does doubling the accelerating voltage
of the electron gun in a cathode ray tube
affect the speed of the electrons that reach
79. The electron gun of a TV picture tube has an
accelerating potential difference of 15 kV and
a power rating of 27 W.
a) How many electrons reach the
screen per second?
b) What speed does each electron have?
80. The electrod