Physics 5054 · O Level · Magnetic effect of a current
Magnetic effect of a current — practice question
Inside a cathode-ray oscilloscope (c.r.o.), an electron beam is generated by a filament at one end of an evacuated glass tube. The electrons are then accelerated and hit a screen at the opposite end of the tube.
(a)[3]
Describe how the filament produces the electrons and how they are then accelerated.
(b)[1]
Explain why the glass tube is evacuated.
(c)[2]
The instruction booklet for a c.r.o. says that strong magnets must not be kept near the c.r.o. Explain why a strong magnet close to the c.r.o. causes the electron beam to be deflected.
Worked solution & mark scheme
This 6-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Heating the filament causes thermionic emission” …