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TABLE OF CONTENTS
LIST OF FIGURE
Figure 2.1 Ilustration of Black Body Radiation Figure 2.2 Spectral Distribution Of Blackbody Radiation At Temperature Different Figure 2.3 Rayleigh's and Jeans' Laws Fail to Explain Experimental Results on the Emission Spectrum of Blackbody Radiation Figure 3.1 Complete set of black body radiation experiment equipment used. Figure 3.2 Computer display of the CASSY LAB program.
CHAPTER I
INTRODUCTION
A. Background A black body is an object that absorbs all the radiation that falls on it. No radiation can escape or be reflected. However, in classical physics, in theory a black body must also emit all possible wavelengths of energy, because only from this can the energy of the object be measured. Even though it's called a black object, it doesn't have to be completely black because it also has to emit energy. The amount and type of electromagnetic radiation it emits depends on the temperature of the black body. Black bodies with temperatures below about 700 kelvin emit almost all of their energy in the form of infrared waves, very little in visible wavelengths. The higher the temperature, the more energy is emitted in visible wavelengths starting from red, orange, yellow and white. The term "Black Body" was first introduced by Gustav Robert Kirchhoff in
- The light emitted by a black body is called black body radiation. If we pay attention to the iron when it is joined (welded). The iron parts to be joined must be heated first. When heated, iron appears reddish. Then, if it continues to be heated, the color of the light emitted by the iron will become bluish. Why is that? Heated iron emits energy or electromagnetic waves which can be visible light. The energy emitted by an object due to the influence of its temperature is called thermal radiation. Thermal radiation is always present in every object, but not all of this thermal radiation can be seen by the eye. Some objects easily absorb radiation, some easily emit radiation and vice versa. An object that can absorb all the radiation it receives and emit all the radiation it emits is called a black body. A black body is modeled as a cavity with a very small opening gap. If radiation enters the cavity through a hole, the radiation will be reflected repeatedly by the walls in the cavity so that the energy is completely absorbed. No reflected radiation radiates out of the hole because the hole is very small. So, this small hollow cavity behaves as a black body because it can absorb all
the radiation it receives. Likewise, if this cavity emits radiation, no radiation returns to the cavity. Thus, the cavity will also radiate all the energy it emits. The experiment “Measurement of the intensity of black body radiation as a function of temperature” essentially aims to prove the experiment carried out by Max Planck, where the hypothesis proposed by Planck was in conflict with the classical theory of electromagnetic waves which was the beginning of the birth of quantum theory. To determine black body radiation, the method used is to compare the increase in temperature of an object and the properties of its surface, where black bodies absorb heat radiation at all wavelengths. B. Problem Statement Based on the background above, several problems can be formulated as follows:
- How to measure black body radiation intensity using thermopile moll?
- How is the intensity of blackbody radiation related to temperature to prove the Stefan-Boltzmann law?
- How to determine Newton's cooling constant? C. Objectives of The Experiment The experiment of measuring the radiation intensity of a black body as a function of temperature (Stefan-Boltzmann Law) and Newtonian cooling has three objectives as follows:
- To find out how to measure the intensity of black body radiation using a thermopile moll.
- To show the relationship between the intensity of blackbody radiation and absolute temperatue, to prove the Stefan-Boltzmann law.
- To determine Newton’s constant of cooling. D. Practical Benefits Based on the practical objectives above, the benefits of the practical activity of radioactive substances are as follows:
- Theoretical benefits a. Students understand how to measure the intensity of black body radiation using a Moll thermophile.
CHAPTER II
LITERATURE REVIEW
The radiation emitted by an object due to its temperature is called thermal radiation. All objects emit this kind of radiation into their environment and also absorb radiation from their environment. If an object initially has a higher temperature than its surroundings, then the object will get colder because the energy it emits is greater than what it absorbs. (Nurlina and Bancong, 2020: 4). The first sign that the classical wave picture of electromagnetic radiation (which successfully explained the experiments of Young and Hertz in the nineteenth century and could be precisely analyzed with Maxwell's equations was not entirely correct, was concluded from the failure of wave theory to explain the observed spectrum of thermal radiation. The type of electromagnetic radiation emitted by various objects is not only caused by their temperature (Krane, 2008). A black body is an ideal object that absorbs all electromagnetic radiation that hits it and does not reflect or re-emit the radiation. This means that a black body has an absorbance and emissivity of 1 or 100%. Emissivity is the ratio of the power emitted by the surface of an object to the power emitted by a black body at the same temperature. Absorptance is the ratio of the radiation flux absorbed by an object to the radiation flux hitting that objec. (Astuti and Handayani, 2018: 67).
Figure 2.1 Ilustration of Black Body Radiation (Source: Jati and Rivai, 2019: 66) A small hole in the wall of a cavity can be considered a practically perfect black body. When radiation energy enters through the hole, there is no possibility of it coming out of the hole again. Radiant energy will be reflected many times by the inside of the cavity, and each time it is reflected, the intensity will decrease according to the absorption coefficient of the cavity walls. Thus, it can be said that
any radiation energy that falls on the hole will be completely absorbed. Therefore, if there is radiation coming out of the hole, it can be considered black body radiation. For this reason, the cavity can be heated to a temperature T so that radiation energy will come out of the cavity. (Nurlina and Bancong, 2020: 6). Black body radiation is electromagnetic radiation emitted by an ideal object that absorbs all radiation that hits it. The distribution of black body radiation energy at various wavelengths has a unique characteristic, namely the existence of a maximum value at a certain wavelength. The location of this maximum value depends on the temperature of the object, where the higher the temperature, the maximum value will shift towards shorter wavelengths (Jati and Rivai, 2019: 66). Planck considered that the exchange between radiant energy and matter must be discrete. Planck's law describes the distribution of radiant energy as a function of temperature and wavelength. Stefan-Boltzmann law, which expresses how the radiative power of a black body increases exponentially as temperature increases(Amalia and Wahyuni, 2023: 108) To investigate the spectrum of black-body radiation, a distribution function is defined which is called the spectral radiation distribution. The term "spectral" in "spectral radiation distribution" explains that the radiation distribution is formulated to describe the radiation contributed by each component of the spectrum. Because the radiation in the spectrum components also depends on the blackbody temperature, the distribution function of the spectral radiation also depends on the blackbody temperature. (Nurlina and Bancong, 2020: 7).
Figure 2.2 Spectral Distribution Of Blackbody Radiation At Temperature Different (Source: Nurlina and Bancong, 2020: 8) Figure 2 shows the distribution of electromagnetic radiation emitted by a black body at various temperatures. The curve depicts the amount of energy emitted at
Rayleigh-Jeans theory is suitable for low frequencies, which means that the average energy of each variety should depend on the frequency. At low frequencies, the average energy of each variety has a value of kBT, while at high frequencies, the average energy of each variety has a value of zero. This thought led Planck to formulate the correct theory. Even though the steps taken by Rayleigh and Jeans were consistent with existing theories at that time, Planck tried to propose a completely new hypothesis. Planck put forward the hypothesis that the energy of each variation cannot be any value from zero to infinity, but must be one of a series of discrete values that are uniformly separated by the interval ∆ε. So, the energy of each variance must be one of the values zero, ∆ε,2∆ε,3∆ε,…,n∆ε, where n is an integer (Nurlina and Bancong, 2020: 14). Interestingly, Max Planck discovered a mathematical equation that was supported based on the experiments he carried out. The equation is the result of interpolation between the Wien equation and the Rayleigh Jeans equation. The equation is:
𝐸(𝑣, 𝑇) = 8𝜋ℎ𝑐 (^3) 𝑒ℎ𝑣^ 𝑣⁄𝑘𝑇 (^3) −1 (2.3)
Where ℎ is Planck's constant, 𝑐 is the speed of light, 𝑇 is the absolute temperature and 𝑘 is Boltzmann's constant. Equation (1) above is also known as Planck's Law of Black Body RadiationRadiation (Nasution, et al., 2023: 60-61).
BAB III
EXPERIMENT METHOD
A. Day/Time Day : Monday, November 1 2021 Time : 10.00 – 12.00 WITA Place : At the Modern Physics Laboratory, Department In Physics, Faculty of Mathematics and Natural Sciences, Makassar State University. B. Tools and materials
- Electric oven device for voltage 230 V 1 piece
- Thermophile Moll 1 piece
- CASSY sensor 1 piece
- μV sensor 1 piece
- NiCr-Ni adapter 1 piece
- Universal clamp 1 piece
- 1.5 mm NiCr-Ni temperature sensor 1 piece
- Black object accessory 1 piece
- V-shaped supports, 28 cm 1 pcs
- Leybold multiclamp 1 piece
- Paired cable 100 cm 1 piece
- Small optical bench 1 piece
- Electric oven stand 1 piece
- Immersion pump 12 V 1 piece
- Silicone tubing, 7 mm 1 piece
- Laboratory bucket, 10 L 1 piece
- PC and CASSY Lab Application 1 piece
- Thermometer 1 piece
- Gas Lighter 1 piece C. Identification Variable
- Measured Variable : Time t (s) Temperature T (℃), Room Temperature Ts (℃)
Figure 3.1 Complete set of black body radiation experiment equipment used.
- Connect all tool components to a PLN voltage source, including the computer.
- The glass window on the thermopile mol is removed.
- The water pump is started and the rubber pipe from the water flow is ensured to be properly connected to the heating oven. Let the water run for approximately 2 minutes before turning on the oven.
- The computer is turned on by opening the CASSY LAB application.
- The NiCr-Ni temperature sensor and μV box are activated.
- Click the CASSY icon on the computer, then wait a moment until a display like figure 3.2 appears.
Figure 3.2 Computer display of the CASSY LAB program.
- The black box to the right of the top is clicked to bring up the Temperature dialog box and you will see a display of changes in temperature that occur due to ongoing heating.
- The second black circle on the left is clicked to bring up the UA1 Voltage dialog box which will display the voltage which indicates the amount of radiation emitted by the heated black body in μV units.
- Temperature in the settings section on the right is clicked to set the temperature measurement range from -100℃ ... 200℃ as well as the U voltage with a voltage range from -3 mV ... 3 mV.
- The electric oven in the laboratory does not work, so it is heated using a portable gas torch.
- Changes in radiation intensity are observed as a function of increasing temperature. Data recording starts when the temperature reaches around 30 ℃ until it reaches 160 ℃ by pressing the F9 key to start data recording
- The portable gas torch is extinguished when the temperature reaches 208 ℃ and the cooling process begins until the temperature reaches 30 ℃.
- After reaching 30 ℃, the recorded data is saved by pressing the F2 key or the save symbol on the CASSY menu.
- The ambient/room temperature is measured using a thermometer. F. Work Principle The black body radiation experiment consists of two processes, namely heating and cooling, this process uses Gas Torch Flame Gun to heat an electric Oven equipped with black body accessories that function as an ideal black body. The temperature sensor uses a NiCr-Ni thermocouple which is connected to the CASSY data logger to a computer CASSY lab program on a computer with a certain temperature range. After the temperature reaches a certain value, the Gas Torch Flame Gun is turned off and the cooling measurement process begins. So that the voltage U is obtained which interprets the radiation intensity measured by a thermopile moil, then connected to the μV sensor, while the temperature (T) is measured using a NiCr-Ni thermocouple which is then connected to the CASSY sensor so that the voltage values U and r will appear on the CASSY program computer screen.
b. Where Newton's law of cooling uses the equation:
𝑙𝑛 𝑇(𝑡)−𝑇𝑠𝑇 0 −𝑇𝑠 = −𝑘𝑡 (3.12)
c. Analysis of graphs with linear equations shows 𝑦 = 𝑚𝑥 + 𝑐 so we get k value, where k = -m. d. Calculate the degree of truth of the relative error, and the uncertainty k with the equation following:
- Degrees of truth DK = R^2 x 100 % (3.5)
- Relative error KR = 100 % - 94,04 % (3.6)
- Uncertainty ∆k = 𝐾𝑅×𝑘100% (3.7)
- Significant figure 𝐴𝐵 = 1 − 𝑙𝑜𝑔 (∆𝑘𝑘 ) (3.8)
- Physics report k = |k ± ∆k| (3.9)
BAB IV
RESULTS AND DISCUSSION
A. Obseravtion Result Activity 1. Measurement of Radiation Intensity as a Function of Temperaturer Incease Table 1. Measurement of Radiation Intensity as a Function of Temperature Increase Time (s) Temperatur (K)
Voltage (V)
Log T (K) Log U (V)
Activity 2. Measurement of Radiation Intensity as a Cooling Function Ts = |27,0 ± 0,5|⁰C Table 2. Measurement of Radiation Intensity as a Cooling Function Time (s) Temperature (K) Voltage (V) 𝑳𝒏 (𝑻 𝑻(𝒕𝟎) −^ − 𝑻𝒔^ 𝑻𝒔 ) 0 488.15 0.00132 0 60 481.15 0.00126 - 0 , 015 120 473.35 0.00119 - 0 , 033 180 465.65 0.00113 - 0 , 05 240 458.65 0.00107 - 0 , 066
B. Data Analysis
Activity 1. Measurement of the Light Intensity of Black Body Radiation as a Function of Temperature (Stefan-Boltzmann Law) Graph 4.1. Relationship between Log T (K) and Log U (V) a. In theory Log U (V)
- TABLE OF CONTENTS........................................................................................
- LIST OF FIGURES................................................................................................
- LIST OF GRAPHICS.............................................................................................
- CHAPTER I INTRODUCTION...........................................................................
- A. Background.......................................................................................................
- B. Problem Formulation.........................................................................................
- C. Objective of Experiments..................................................................................
- D. Benefits of Experimentation..............................................................................
- CHAPTER II THEORETICAL BASIS................................................................
- CHAPTER III EXPERIMENTAL METHODS.................................................
- A. Place and Time of Implementation..................................................................
- B. Tools and Materials..........................................................................................
- C. Identification Variable.....................................................................................
- D. Definition Operational Variables....................................................................
- E. Work Procedures.............................................................................................
- F. Working Principles..........................................................................................
- G. Data Analisys Technique.................................................................................
- CHAPTER IV OBSERVATION RESULTS.......................................................
- A. Observations Results.......................................................................................
- B. Data Analisys...................................................................................................
- C. Discussion.......................................................................................................
- CHAPTER V CLOSING.....................................................................................
- A. Conclusion......................................................................................................
- B. Suggestion.......................................................................................................
- BIBLIOGRAPHY................................................................................................
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- 4920 327.05 0.00014 - 0 ,
- y = 7,6191x - 23, M = 𝜎 𝑇4 log
- R² = 0,
- -4,
- -3,
- -2,
- -1,
- -0,
- 2,45 2,5 2,55 2,6 2,65 2,7 2,
