Lab 3: Joule Heating of a resistor
Objectives
The objectives are:
• Showing that the system's temperature increases in direct proportion to the amount of power applied
• So that we may compare the experimental value of J to the known value and draw our conclusions.
Apparatus
• Standard calorimeter immersion heater coil
• Various thermometers and callipers
• Electricity source that is directly connected (5A at 6V)
• 0-5A ammeter, 0-10V voltmeter
• Timer for the lab
• Mass gauges and balances for the laboratory.
Theory
The power from a resistor is given as: P = I²R = V²/R = VI.
The heat absorbed is given as:
Q= mc Δ T
All of the energy that the resistor absorbs from the electrical current ends up as heat. Here is the information provided:
U ( joules)=J ( joules / calorie )*Q ( calories )
Procedure
• We measured and recorded the calorimeter cup's mass mc.
• Next, submerge the resistor coil entirely in the calorimeter cup by adding adequate water. A few degrees below room temperature should be the water temperature. Next, weigh the water and the calorimeter cup and make a note of the result. The mass of water was recorded as mw after the subtraction process.
• Afterwards, insert the immersion heater into the calorimeter container. Make sure the immersion heater is positioned below the water level by checking it again.
• Then I adjusted the current to approximately 2 amperes and turned on the power source. Perform this swiftly, and then, while keeping the output level set to the setting that generated 2A, turn off the power.
• Identified and documented the starting temperature, Ti. We estimated all temperature readings to within 0.1 C using thermometers.
• So long as the power supply is maintained at the 2A output level. I started the laboratory timer at the same time as I turned on the power source. Noted the starting points for the voltage and current I. The temperature (T), current (I), and voltage (V) were monitored every 60 seconds for eight minutes.
Data Analysis
The data is shown in table below:
Mass of calorimeter and water = 179g
Mass of calorimeter = 50g
Mass of water = 129g
Initial temperature = 15C
Ccal = 0.22 cal/gC
Cw = 1 cal/gC
Data Table
t (s) I (A) V (V) T (°C)
0 4 4.5 17
60 4 4.5 18
120 4 4.5 19
180 4 4.5 20
240 4 4.5 22
300 4 4.5 23
360 4 4.5 25
420 27
480 29
Discussion
The objective of this experiment was to experimentally confirm the linear relationship between the temperature rising after passing the electricity through the resistor and proving the experimental value of the constant J (Joule's constant). Table indicates a distinct rise in temperature as time goes primarily, this means that heat is created as the electrical current is allowed to pass through the system. The connection between power, current, voltage, and heating temperature fits the theory. Thus, the concept of Joule heating is validated.
In discussion, we see that a correlation develops between the temperature and the energy input related to electricity, as the current and voltage levels grow, that simultaneously results in higher temperatures over time. Furthermore, the J value that is based on the data can be calculated, bringing light to the degree or the efficiency at which the energy conversion from electrical to thermal energy happens.
Conclusion
In summary, the experiment experimentally demonstrated the capability of the electrical input energy to increase temperature as Joule's law states. The calculated experimental value of J can be compared with the real one in order to check the accuracy of the experiment and the efficiency of energy conversion. The above outcomes afford an understanding of principles of electrical heating and energy transfer.