A black, totally absorbing piece of cardboard of area intercepts light with an intensity of from a camera strobe light. What radiation pressure is produced on the cardboard by the light?
The radiation pressure is, .
Area of cardboard, .
Intensity, I = 10 W/m2.
The radiation pressure formula is for the total absorption of radiation. First, find the force on the surface due to radiation, and substituting this value and the area of the surface, calculate the radiation pressure of the light bulb. When electromagnetic radiation of intensity is incident on a perfectly reflective surface, the radiation pressure exerted on the surface is given by, , where is the speed of light.
If the radiation is totally absorbed by the surface, the force is,
Here I is the intensity of radiation, and is the area of the surface perpendicular to the path of the radiation.
The intensity is related to the power of the bulb P as,
Where, A is the area of the cardboard.
The radiation pressure Pr is the force per unit area, and it can be calculated as,
Substitute the values in the expression, and we get,
Therefore, the radiation pressure is .
(a) Prove that a ray of light incident on the surface of a sheet of plate glass of thickness emerges from the opposite face parallel to its initial direction but displaced sideways, as in Fig. 33-69. (b) Show that, for small angles of incidence , this displacement is given by
where is the index of refraction of the glass and is measured in radians.
When the rectangular metal tank in the Figure is filled to the top with an unknown liquid, the observer , with eyes level with the top of the tank, can just see the corner . A ray that refracts toward the top surface of the liquid is shown. If so, what is the index of refraction of the liquid?
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