How to determine temperature of filament?

In summary, the conversation discusses the process of determining the temperature of a filament in an incandescent light bulb to determine thermal energy output through radiation. The Stefan-Boltzmann law and a test circuit were used to calculate the temperature, but the individual is unsure how to determine the temperature from knowledge of circuits. The conversation also mentions estimating temperature from a glowing object's spectrum and calculating it from specific heat and heat radiation rate in a vacuum.
  • #1
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I was wondering in class today how I could determine the temperature of a filament in an incandescent light bulb? Mainly then so I could determine the thermal energy outputted through radiation. So after school I used a test circuit.

I started with the Stefan-Boltzmann law which is Q = (ε)(σ)(T4)(A)(t)
First I substituted 60s into the equation as my time, 0.191 as my emissivity constant and for Area I measured 1.1x10-5m2

So finally I got Q = (60s)(0.191)(5.670367 W/m2K4*10-8)(1.1x10-5m2)(T4) ⇒ Q = 7.1480646402×10-12(T4)

I am so close to my answer but I simply don't know how to figure out how to get temperature from my knowledge of circuits!
I had my powersource to stay at 4.0 Volts and my lightbulb was 1.44 Watts type so we just turn that into
1.44W = 4.0V(I) ⇒ (1.44W/4.0V) = I ⇒ 0.36 amperes = I
and for resistance it is just 4.0V = 0.36A(R) ⇒ 4.0V/0.36A = R ⇒ 11Ω ≅ R.

From there I have no idea of how to determine the temperature of the filament so any and all help would be appreciated, thank you!
 
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  • #2
Welcome to PF;
The temperature of a glowing object is usually estimated from its spectrum.
You could calculate it from theory from specific heat, and the rate that heat is radiated away (if the filament is in vacuum)... knowing that this is a steady state.
 

1. How do you measure the temperature of a filament?

The temperature of a filament can be measured using a thermometer or a thermocouple. The thermometer is placed near the filament and measures the temperature of the surrounding air. A thermocouple, on the other hand, can be attached directly to the filament to measure its temperature.

2. What is the ideal temperature for a filament?

The ideal temperature for a filament depends on the type of material it is made of. Generally, most filaments require a temperature range of 180-260°C for optimal printing results. It is important to refer to the manufacturer's instructions for the specific filament being used.

3. How can I accurately calibrate the temperature of my 3D printer's hot end?

To accurately calibrate the temperature of your 3D printer's hot end, you can use a temperature calibration tool or software. These tools allow you to set a desired temperature and then adjust the temperature of the hot end until it reaches the desired temperature. This process may need to be repeated multiple times for accuracy.

4. Why is it important to have the correct temperature for a filament?

The correct temperature is important for a filament because it directly affects the quality of the 3D printed object. If the temperature is too low, the filament may not melt properly and can result in a weak and brittle print. If the temperature is too high, the filament may burn or become too runny, causing the print to fail.

5. Can I use the same temperature for all types of filaments?

No, different types of filaments require different temperatures for optimal printing. For example, PLA filaments typically require a lower temperature compared to ABS filaments. It is important to refer to the manufacturer's instructions for the specific filament being used and adjust the temperature accordingly.

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