11 posts • Page 1 of 1
Intensity of light is measured as the rate at which energy is delivered to a unit of surface in terms of energy per unit time. EM energy is energy that is emitted from objects in the form of electrical and magnetic waves. Energy according to the equation E = hv, as well as c = lambda*v, depends on the frequency and the wavelength.
During the photoelectric experiment, light was acting as a particle. When the intensity of light was increased, only the number of photons increased. However, each photon still did not have sufficient energy to eject an electron. When the frequency of the light was increased, the energy of each photon increased, and the photons had enough energy to eject the electrons.
In terms of a photoelectric experiment, the intensity is determined by the number of photons present. That's why increasing the intensity in a photoelectric experiment did not yield more electrons being ejected. Energy however is determined by frequency and the frequency has a minimum value depending on the metal.
In the photoelectric experiment, light was acting as a particle known as a photon. Increasing the intensity of the light changed only the number of photons being used and nothing else. This is why increasing intensity did not affect the electrons being emitted. A single photon must have enough energy to cause an electron to be emitted from the metal surface, so increasing energy would change how the electron was emitted by increasing its kinetic energy. Changing the frequency of the light allows one to change the energy of the photon, which had a direct effect on the electron being emitted.
The intensity of a wave is defined by the number of photons it contains. The energy of the wave, however, refers to its frequency as the energy of the photons only increases with an increase in frequency. For example, when the intensity of the wave was increased in the photoelectric experiment for light with high frequency, the number of photons interacting with the surface has increased, causing more electrons to be ejected because more photons hit the metal surface per unit time. At low frequencies, however, no electrons were ejected regardless of the intensity, meaning that increasing the intensity did not increase the energy of the photons, and the photons could not overcome the threshold energy. At high frequencies, even low-intensity light ejected electrons because the energy of the light was high.
The intensity of a light source is directly related to the number of photons and the rate at which they are projected onto the sample. The frequency is not related to the number of photons or intensity.
In the photoelectric experiment, increasing the intensity would only increase the number of photons (like making a light brighter, for example). On the other hand, the researches needed to increase the energy of each individual photon. This is done by increasing the frequency of the EM wave.
Who is online
Users browsing this forum: No registered users and 1 guest