Estimate the approximate maximum defection of the electron beam near the center of a TV screen due to the Earth’s 5.0 X 10-5 T field. Assume the CRT screen (section 17-10) is 22cm from the electron gun, where the electrons are accelerated
(a) By 2.0 kV, or
(b) By 30 kV. Note that in color TV sets, the CRT beam must be directed accurately to within less than 1 mm in order to strike the correct phosphor. Because the Earth’s field is significant here, mu-metal shields are used to reduce the Earth’s field in the CRT.