Why it is sensible to have magnetic screening around the tube of cathode ray oscilloscope?

Why don't we supply to DC to the transformer? Why tube-light makes sound? Houses in 1912? What the scincifics method? Why is ashalt used to make a road surface? Does SGID allow users to execute a binary compiled program? How do we use ubiquitous computing? Why does the water backup out of the wash drain during rinse cycle? Is an earthing continuity required for submersible pump? What does solution oriented mean? What are the three required sets of statements for every function that a programmer writes in C plus plus? How can I improve my skills at the piano? What does a reactor look like? Does a tub need a p-trap? What is the Ideal Mechanical Advantage of a lever that has a fulcrum in the exact center? Is it possible to have pure inductive coil? What is the difference of asme b18.21.1 type a and astm f436? The survival recovery center src does which? What are the Subject matter of technical writing? Significance of workshop practice in engineering first year?