# What is the Gauge Pressure Inside a Hot Gas-Filled Incandescent Light Bulb?

• MidgetDwarf
C, assuming the gas inside is at atmospheric pressure when the bulb is at 20.0 °C. He attempts to use the formula (p/t)=(p'/t') with the given temperatures and atmospheric pressure of 1atm, but is unsure about the difference between gauge, atmospheric, and absolute pressure and how to convert between them.
MidgetDwarf

## Homework Statement

Suppose a gas-filled incandescent light bulb is manufactured so that the gas inside the bulb is at atmospheric pressure when the bulb has a temperature of 20.0 °C. Find the gauge pressure inside such a bulb when it is hot, assuming its average hot temperature is 65.0 °C.

## Homework Equations

(p/t)=(p'/t') where the left hand side is initial pressure and temperature, the right is the when hot.

t= 293.15 K
t'=338.15 K

the gas inside is at atmospheric pressure.

## The Attempt at a Solution

1atm= 1.013x^5 Pa[/B]

i use the formula above, and solve for p'

p' = (pt')/t

p'=(1.013x10^5)(338.15)/(293.15) (Pa*K)/(K) (the right stuff are the units of measurement used)

116850.0597 Pa.

However, I am not getting the answer. I never took a chemistry class, so I am unsure what the difference between gauge pressure/ atmospheric/ absolute pressure is and how to convert it.

I believe my formula is correct but I am not using the correct pressure values.

Chet

## 1. What is the pressure inside a lightbulb?

The pressure inside a lightbulb is typically very low, ranging from 0.1 to 0.3 atmospheres. This is because the bulb is filled with an inert gas, such as argon or nitrogen, which exerts minimal pressure on the walls of the bulb.

## 2. How does the pressure inside a lightbulb affect its performance?

The pressure inside a lightbulb does not directly affect its performance. However, it can indirectly impact the lifespan of the bulb. Higher pressures can cause the filament to degrade faster, leading to a shorter lifespan.

## 3. Does the pressure inside a lightbulb change as it heats up?

Yes, the pressure inside a lightbulb does change as it heats up. As the temperature rises, the gas particles inside the bulb move more rapidly, increasing the pressure. This is known as thermal expansion.

## 4. Can the pressure inside a lightbulb be measured?

Yes, the pressure inside a lightbulb can be measured using a pressure gauge. However, specialized equipment is needed to accurately measure the low pressures inside a lightbulb.

## 5. What happens if the pressure inside a lightbulb is too high?

If the pressure inside a lightbulb is too high, it can cause the bulb to explode due to the buildup of internal stress. This is why lightbulbs are designed to withstand a certain range of pressures to prevent accidents.

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