The Photoelectric Effect and Measuring Planck`s Constant
... the cathode and captured by the anode. Unfortunately, the measure current includes dark current (current when no light is present) and the current associated with electrons eject by incident light from the anode and captured by the cathode. ( Note in this case, in a formal sense, the names cathode a ...
... the cathode and captured by the anode. Unfortunately, the measure current includes dark current (current when no light is present) and the current associated with electrons eject by incident light from the anode and captured by the cathode. ( Note in this case, in a formal sense, the names cathode a ...
Pre and Post Visit Materials for Shock Value
... Electromagnet – a type of magnet where the magnetic field is created by an electrical charge ...
... Electromagnet – a type of magnet where the magnetic field is created by an electrical charge ...
Module 6: Field Emission Display
... cathode is very small, the pressure can increase by several orders of magnitude. If a pumping source is capable of maintaining a vacuum of ~10 -8 T, then a vacuum at a location a centimeter away from the source could be 10 -5 T, when the separation distance between the anode and cathode is the dista ...
... cathode is very small, the pressure can increase by several orders of magnitude. If a pumping source is capable of maintaining a vacuum of ~10 -8 T, then a vacuum at a location a centimeter away from the source could be 10 -5 T, when the separation distance between the anode and cathode is the dista ...
Photomultiplier
Photomultiplier tubes (photomultipliers or PMTs for short), members of the class of vacuum tubes, and more specifically vacuum phototubes, are extremely sensitive detectors of light in the ultraviolet, visible, and near-infrared ranges of the electromagnetic spectrum. These detectors multiply the current produced by incident light by as much as 100 million times (i.e., 160 dB), in multiple dynode stages, enabling (for example) individual photons to be detected when the incident flux of light is very low. Unlike most vacuum tubes, they are not obsolete.The combination of high gain, low noise, high frequency response or, equivalently, ultra-fast response, and large area of collection has maintained photomultipliers an essential place in nuclear and particle physics, astronomy, medical diagnostics including blood tests, medical imaging, motion picture film scanning (telecine), radar jamming, and high-end image scanners known as drum scanners. Elements of photomultiplier technology, when integrated differently, are the basis of night vision devices.Semiconductor devices, particularly avalanche photodiodes, are alternatives to photomultipliers; however, photomultipliers are uniquely well-suited for applications requiring low-noise, high-sensitivity detection of light that is imperfectly collimated.