BRAINCAKEThe Photoelectric Effect
When a gold-leaf electroscope is negatively charged the leaf and the rod repel each other.A zinc plate is placed on top of the electroscope, and u.v. light is shone on the zinc plate. The gold leaf falls. The incident radiation causes the electrons to be emitted from the zinc. These electrons are known as photoelectronsPhotoelectrons are emitted only when the incident radiation is above a threshold frequencyAbove the threshold frequency, the emission of photoelectrons is instantaneousIncreasing the intensity of the radiation increases the number of photoelectrons emitted and does not increase the maximum kinetic energy of the photoelectrons.
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Key terms in this lesson
- energy
- The capacity of a system to do work.
- kinetic energy
- The energy an object possesses due to its motion.
- frequency
- The number of complete oscillations or wavelengths passing a given point per unit time.
- intensity
- The radiant power passing through a surface per unit area.
- photon
- A discrete packet, or quantum, of electromagnetic energy.
More in Quantum Physics
- The Energy of a Photon and the Planck Constant
- The Electron Volt
- The Photoelectric Effect Equation and Wave-Particle Duality
All 4 lessons in Quantum Physics · All OCR AS-level Physics topics