Laporan Praktikum R-Lab KR02 – Calori Work
Nama: Ahmad Fady Ganis NPM: 1406545301 Fakultas: Teknik Departemen: Program Internasional Program Studi: Teknik Sipil Kode Praktikum: KR-02
Laboratorium Fisika Dasar UPP IPD Universitas Indonesia
Objective To calculate the value of the heat capacity of a wire conductor Apparatus
Voltage source which can vary Conductor wires (with a mass of 2 gr) Thermometer Voltmeter and Ammeter Adjustable power supply Camcorder PC unit with DAQ and remote control
Theoretical Basis The law of conservation of energy states that energy can neither be created nor destroyed, but only changed. This experiment will show that by changing electrical energy into heat energy. Electrical energy resulted from a power source on a conductor that has resistance is formulated by: 𝑊 = 𝑉. 𝐼. 𝑇 Where: W: Electrical energy (joule) V: Electrical voltage (volt) I: Electrical current (ampere) T: Time (second) The heat energy that is resulted from the conductor wires are expressed in the form of temperature raise. The heat needed to raise said temperature is formulated by: 𝑄 = 𝑀. 𝐶. ∆𝑇 Where: Q: Heat needed (calorie) M: Mass of object (kg) C: Specific heat of object (Cal/gr⁰C) ΔT: Change of temperature [T2 – T1] (K) A wire is then tied to the temperature sensor. That wire will be flown by an electricity current so that it dissipates heat energy. The temperature change that happens will be notify the sensor and
will be recorded by the instrumentation system. The voltage given to the wire can be changed so that the temperature change can vary upon the voltage given. Experiment Steps This experiment is done via the R-Lab
Practitioners activate the web-cam by clicking the video icon in the R-Lab page
Practitioners then give a voltage of V0 to the conductor wires
Practitioners turn on the power supply by clicking the radio button beside it
The temperature change data is then taken, which is the voltage and current on the conductor wire for each second for 10 seconds by clicking the “measure” icon
Practitioners then note the temperature of the wire in the web-cam, and wait for it until the temperature returns to the initial temperature
Practitioners repeat steps 2 to 5 with voltages V1, V2 and V3
Task and Evaluation 1. Based on the data acquired, make a graph that depicts a relation between the temperature and time for each voltage 2. For voltages V1, V2 and V3. Calculate the value of (C) of the conductor wires used 3. Based on the value of c acquired, determine the kind of wire used 4. Give the analysis of this experiment!
1. For each voltages the graphs are:
V0: 23.15 23.1 23.05 23 22.95 22.9 22.85 22.8 1
2
3
4
5
6
Series1
7
8
9
10
11
Series2
24.2 24 23.8 23.6 23.4 23.2 23 22.8 22.6 22.4 22.2
V1:
1
2
3
4
5
6
7
8
9
10
35 30 25 20 15 10 5 0
V2:
1
2
3
4
5
6
7
8
9
10
1
2
3
4
5
6
7
8
9
10
35 30 25 20 15 10 5 0
V3:
2. For V1: I=35.48 A and V=0.66 V and t=30-3=27 s 𝐶=
𝑣𝑖∆𝑡 ∆𝑇
=
(0.66)(35.48)(27) 1.2
= 526.88 J/⁰C
For V2: I=51.79 A, V=1.66 V and t=27 s 𝐶=
𝑣𝑖∆𝑡 ∆𝑇
=
(1.66)(51.79)(27) 7.3
= 317.98 J/⁰C
For V3: I=42.43 A, V=1.06 V and t=27 s 𝐶=
3. 𝐶̅ =
𝑣𝑖∆𝑡 ∆𝑇
=
∑3𝑖=1 𝐶𝑖 3
(1.06)(42.43)(27) 2.6
=
= 467.06 J/⁰C
526.88+317.98+467.06
∑(𝐶− 𝐶̅ )2
3
= 437.31 J/⁰C
(526.88−437.31)2 + (317.98−437.31)2 + (467.06−437.31)2
𝑠 = √ 𝑁(𝑁−1) = √
6
= 62.11 J/⁰C
So, the heat capacity of the conductor wires used is 467.06 ± 62.11 J/⁰C The experiment this time is called “calorie work”. This experiment is done via the
4.
R-Lab, which means that the experiment is done with a computer connected to the internet. So practitioners can do this experiment without going to the MIPA Faculty of UI. They can do the experiment anywhere so long they are connected to the internet. The tools used in the R-Lab are actual tools that is displayed via web-cam where the tools are. This experiment is done by flowing electricity to a certain conductor wire. Because of that, a change of temperature happened in the wire. Thus proving that the law of conversion of energy is true where energy cannot be created or destroyed but only converted, where in this case the electricity energy is converted into heat energy. There are 4 voltages used to do this experiment, which are 0 V, 0.66 V, 1.59 V and 1.06 V. This measurement is done within 30 seconds and data recording is done every 3 seconds. For every second, the wire that is flown with electricity will be experiencing a temperature change, except when flown by the 0 V. The result that was acquired from this experiment was not accurate, mostly because of a technical problem where I cannot see the web-cam. Thus I also cannot see if the temperature of the wire has gone back to normal or not so the remaining voltage of the previous voltages may change the outcome of the results. Besides that things like this could happen because a small value of heat has a high value of conductivity and can raise the temperature without much energy. Meanwhile, for a material with a high heat capacity needs a lot of energy to raise the temperature, so it has low conductivity. As for the heat capacity acquired, it is already appropriate with the theory that states the heat dissipated on the wire is proportionate to the change of voltage and electric current
value but it will be inversely proportionate with the heat capacity on the 3 experiments so it will have only a small difference in value. Based on the data processing that is done based on the law of conversion of energy, the electrical energy produced from the power source is changed to heat energy that causes the temperature to go up. Here we can find the heat capacity (energy needed to raise the temperature by 1⁰C) of the conductor wires. Based on the calculations above the heat capacity is 437.31 J/⁰C with an uncertainty value of 62.11 J/⁰C. Which means that the true value of the heat capacity is between (437.31 – 62.11) J/⁰C to (437.31 + 62.11) J/⁰C. Conclusion
When a wire is flown with electricity, the temperature of the wire will rise
The greater the flow of the electricity, the greater the rise of the temperature
A material with low heat capacity means that it has high conductivity, because it can raise the temperature with a little energy
A material with high heat capacity means that it has low conductivity, because it needs a lot of energy to raise the temperature
Energy cannot be created nor destroyed, but it can be converted into other forms. Such in this case is the conversion of electrical energy into heat energy that causes the rise of the temperature of the wires
References Giancoli, D.C.; Physics for Scientists and Engineers, Third Edition, Prentice Hall, NJ, 2000. Halliday, Resnick, Walker; Fundamentals of Physics, 7th Edition, Extended Edition, John Wiley & Sons, Inc., NJ, 2005.
