What invention has a cathode which accelerates electrons toward an anode, passing the electrons through a magnetic field and onto a phosphorescent screen?

What invention has a cathode which accelerates electrons toward an anode, passing the electrons through a magnetic field and onto a phosphorescent screen?

• A. Transistor
• B. Cathode ray tube (CRT)
• C. Solar cell
• D. Camera

Answer: (B)

The main idea here is how an electron beam is created and directed to produce a visible image on a phosphorescent surface. In a cathode-ray tube, a heated cathode emits electrons, which are then accelerated toward a positively charged anode. The beam passes through magnetic fields created by deflection coils, which steer it across a phosphorescent screen. When the fast electrons strike the phosphor coating, they make it glow, forming an image. This combination of electron emission, acceleration, magnetic deflection, and a phosphorescent screen is characteristic of a cathode-ray tube. Transistors are solid-state devices that control electric current in circuits, not electron beams on a screen. Solar cells convert light into electricity, without producing a phosphorescent display. Cameras capture light with a sensor or film, not by directing a beam to a phosphorescent screen.

The main idea here is how an electron beam is created and directed to produce a visible image on a phosphorescent surface. In a cathode-ray tube, a heated cathode emits electrons, which are then accelerated toward a positively charged anode. The beam passes through magnetic fields created by deflection coils, which steer it across a phosphorescent screen. When the fast electrons strike the phosphor coating, they make it glow, forming an image. This combination of electron emission, acceleration, magnetic deflection, and a phosphorescent screen is characteristic of a cathode-ray tube.

Transistors are solid-state devices that control electric current in circuits, not electron beams on a screen. Solar cells convert light into electricity, without producing a phosphorescent display. Cameras capture light with a sensor or film, not by directing a beam to a phosphorescent screen.