You are conducting a photoelectric effect experiment by shining a light of 500 nm wavelength at a piece of metal and determining the stopping potential. If, unbeknownst to you, your 500 nm source actually contained a small amount of ultraviolet light, would it throw off your results by a small amount, or by quite a bit? Explain.
Yes, the presence of ultraviolet light affects the result by quite a bit as more stopping potential would be required than the one designed for 500 nm light to stop the current.
The presence of a small amount of ultraviolet light in light of wavelength is 500 nm.
Thermal equilibrium: It is a state of equilibrium in which the temperature of both the objects becomes the same and there is no further transfer of heat.
Electromagnetic radiation (EMR) consists of waves of the electromagnetic (EM) field propagating through space, carrying electromagnetic radiant energy.
Light of wavelength, 500 nm is incident on a metal surface. The stopping potential is determined for the photoelectric effect setup. A small amount of ultraviolet light is also present in the light source.
For the photoelectric effect to take place, the wavelength of the incoming light must be greater than that of the threshold wavelength for the given metal. When the wavelength is more than the threshold wavelength, then photoelectrons will be emitted and photocurrent will flow in the circuit. To stop the photocurrent, we apply a certain potential difference across the plates which doesn't allow the electrons to leave the collector plate. This potential difference is called the stopping potential.
The emission of electrons doesn't depend on the intensity of light but only depends on the wavelength of the light. Since the wavelength of ultraviolet light is less than that of 500 nm light, the emission will occur at the potential difference designed for the 500 nm light.
Therefore, the presence of even a small amount of ultraviolet light (low intensity) will affect the result significantly as this will require more stopping potential than the one designed for 500 nm light.
Compton used X-rays of 0.071nm wavelength. Some of the carbon’s electrons are too tightly bound to be stripped away by these X-rays, which accordingly interact essentially with the atom as a whole. In effect me in equation (3-8) is replaced by carbon’s atomic mass. Show that this explains why some X-rays of the incident wavelength were scattered at all angles.
A flashlight beam produces 2.5 W of electromagnetic radiation in a narrow beam. Although the light it produces is white (all visible wavelengths), make the simplifying assumption that the wavelength is 550 nm, the middle of the visible spectrum. (a) How many photons per second emanate from the flashlight (b) What force would the beam exert on a “perfect mirror”?
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