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Diffstat (limited to 'blackbody_new.tex')
| -rw-r--r-- | blackbody_new.tex | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/blackbody_new.tex b/blackbody_new.tex index e892162..80c40ad 100644 --- a/blackbody_new.tex +++ b/blackbody_new.tex @@ -77,7 +77,8 @@ Imagine a metal wire connected to a cold reservoir at one end and a hot reservoi \end{figure} \\ \textbf{Important}: When using the thermal radiation sensor, make each reading quickly to keep the sensor from heating up. Use sheets of white isolating foam (with the silvered surface facing the lamp) to block the sensor between measurements. \\ -\textbf{Sensor calibration}: To obtain the radiation sensor readings $V_S$ for radiated power per unit area $S$ in the correct units ($W/m^2$), you need to use the voltage-to-power conversion factor $22~V/W$, and the area of the sensor $2mm\times2mm$: +\textbf{Sensor calibration}: To convert the radiation sensor readings $V_S$ +to the detected thermal radiation intensity $S_{det}$ (power per unit area), you need to use the voltage-to-power conversion factor $22~V/W$, and the area of the sensor $2mm\times2mm$: \begin{displaymath} S_{det}[W/m^2]=\frac{V_S [V]}{22 [V/W]}\cdot \frac{1}{4\cdot 10^{-6}[m^2]} @@ -184,7 +185,11 @@ power supply, meter stick. \end{figure} A point source of radiation emits that radiation according to an inverse square law: that is, the intensity of the radiation in $(W/m^2)$ is proportional to -the inverse square of the distance from that source. This way, the intensity at the certain distance from the blackbody integrated over surface of the sphere of such radius is always constant. Mathematically, we expect the following relationship between the total power of the radiation source $P_0$ and the distance to the point source $r$ to be: +the inverse square of the distance from that source. This way, the +intensity at the certain distance from the blackbody integrated over +surface of the sphere of such radius is always constant. Mathematically, we +expect the relationship between the detected intensity $S_{det}$, +the total power of the radiation source $P_0$, and the distance to the point source $r$ to be: \begin{equation} \label{invlaw_theory} S_{det}(r)=\frac{P_0}{2\pi r^2} \end{equation} |