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Cathode ray tube
Intermediate
Electron beams steered by electric fields.
Electrons accelerated through a potential and deflected by plate fields strike a phosphor screen. Old TVs and oscilloscopes used it.
Deflection the deflection is proportional to the plate voltage.
The beam must travel in a vacuum.
In more detail
A cathode ray tube accelerates electrons and steers them with electric or magnetic fields to form an image. Electrons hit a phosphor screen, which glows where they land.
Real-world uses
- Older televisions and oscilloscopes used cathode ray tubes.
- Electron microscopes use similar electron optics.
- Old television sets and oscilloscopes used electric fields to steer electron beams across a screen.
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Frequently asked questions
Why are CRTs being replaced?
Modern flat screens are thinner, lighter and use less power.
How are electrons steered?
Electric deflection plates or magnetic coils change their direction.
How does an oscilloscope use electric fields?
Voltages on deflection plates bend the electron beam, so the trace shows the input signal over time.
Related topics in Electrostatics
Photocopiers and electrostatic precipitators · Millikan oil drop experiment · Motion of charge in uniform field · Method of images · Poisson's and Laplace's equations · Multipole expansion