Question

Why does an incandescent light have a longer life when an inert gas is used rather than a vacuum? 1\. The filament vaporizes more slowly. 2\. Heat is removed from the filament. 3\. The bulb is less likely to implode when subjected to vibration. 4\. The gas directly absorbs energy from the electrons in the filament.

Short answer

An incandescent light bulb has a longer life when an inert gas is used instead of a vacuum because the inert gas reduces the evaporation of the filament material, causing the filament to vaporize more slowly. This contributes to increasing the lifespan of the bulb.

Step-by-step solution

Examine the options

First, we should look at each of the four explanations provided and see which one correctly answers the question.

Eliminate incorrect answers

Let's analyze each option: 1. "The filament vaporizes more slowly." Filling a light bulb with an inert gas can make the filament vaporize more slowly, as the inert gas reduces the evaporation of the filament material. This aspect contributes to increasing the lifespan of the bulb. 2. "Heat is removed from the filament." Inert gases do not actively transfer heat away from the filament. Instead, they help prevent the filament from overheating by reducing evaporation. So, this answer is not correct. 3. "The bulb is less likely to implode when subjected to vibration." While it is true that having a gas inside a bulb can make it slightly more durable, this factor does not have a significant impact on the bulb's overall life. Therefore, this answer is not the primary reason for a longer lightbulb lifespan with the use of an inert gas. 4. "The gas directly absorbs energy from the electrons in the filament." Inert gases do not absorb significant amounts of energy from the filament's electrons. They may, to an extent, help in reducing the temperature by dissipating heat throughout the bulb. However, this is not a major factor in a lightbulb's life. So, this answer is incorrect.

Choose the correct answer

After analyzing each explanation, option 1 ("The filament vaporizes more slowly") is most closely related to the reason an incandescent light bulb's lifespan increases when using an inert gas instead of a vacuum. The reduction of filament evaporation is the primary reason for the increased life of an incandescent bulb filled with an inert gas.

Key concepts

Incandescent Light

Incandescent light refers to the glow emitted by a filament when it is heated to high temperatures within a light bulb. This glowing phenomenon occurs due to the filament's resistance to the electric current flowing through it. The electrical energy is thus transformed into light and heat. A typical incandescent light bulb consists of a thin filament made of tungsten housed in a glass envelope.

When the electric current passes through the tungsten filament, it heats up to become extremely hot, producing visible light. However, this heating process also leads to some drawbacks, such as the filament's tendency to slowly evaporate over time, which can result in the bulb burning out. Therefore, manufacturers strive to extend the lifetime of these bulbs by minimizing filament evaporation.

Educational Problem Solving

Educational problem solving involves analyzing different scenarios, evaluating possible solutions, and determining the most accurate one. When faced with a physics problem, such as understanding why using inert gas prolongs the life of an incandescent bulb, it is essential to methodically evaluate each given option.

Steps to effective problem solving in education usually involve:

• Identifying the problem: Carefully examining the question or situation at hand.
• Exploring potential solutions: Looking at all options and possible explanations.
• Eliminating incorrect options: Analyzing each option to discard the ones that do not make logical sense.
• Confirming the correct answer: Selecting the most scientifically accurate explanation that addresses the core question.

Following these steps ensures a deeper understanding of the topic and strengthens critical thinking skills.

Inert Gases

Inert gases, also known as noble gases, include elements such as argon, neon, and helium. They are characterized by their low chemical reactivity due to having a complete electron shell. In the context of incandescent bulbs, the use of inert gases plays a crucial role in prolonging their lifespan.

When housed within a light bulb, inert gases help mitigate filament evaporation and tungsten evaporation. These gases create a buffer against the vacuum, slowing down the rate at which the hot tungsten atoms escape from the filament surface. They achieve this by reducing collisions with evaporating tungsten atoms, hence minimizing material loss. This results in increased bulb longevity while also ensuring safer operation by reducing the chance of the bulb weakening over time due to material depletion.

Filament Evaporation

Filament evaporation is a process where the heated tungsten filament inside the bulb starts to evaporate or sublime over time. This is the reason behind why an incandescent light bulb eventually burns out. As the tungsten continues its cycle of vaporization, it gradually weakens until it breaks, leading to bulb failure.

In bulbs with an inert gas, the rate of filament evaporation is significantly lowered. The inert gas provides an environment where tungsten atoms are less likely to escape the filament surface because of reduced pressure difference compared to a vacuum. Consequently, this prevents rapid thinning of the filament, resulting in a longer lifespan for the bulb.

Understanding filament evaporation helps in appreciating the efficiencies introduced by filling incandescent bulbs with inert gases. This knowledge ensures anyone studying the longevity of light bulbs can comprehend the integral role of the chosen environment inside the bulb.