Who invented the thermos flask, also called the vacuum flask, which keeps liquids hot or cold by using an insulating vacuum layer?

Introduction / Context:

The thermos flask, also known as the vacuum flask, is a common household item used to keep beverages hot or cold for long periods. It relies on the principle that a vacuum is a very poor conductor of heat. This question asks you to identify the scientist who invented this device, a fact that appears in general science and inventions based questions.

Given Data / Assumptions:

• The object in question is the thermos or vacuum flask.
• The question asks who invented it.
• The options include scientists known for different contributions to science and technology.
• You need to connect the vacuum flask specifically with the correct inventor.

Concept / Approach:

Sir James Dewar, a Scottish chemist and physicist, invented the vacuum flask in the late nineteenth century. He developed it as a laboratory device to store liquefied gases at very low temperatures. The flask consists of two walls with a vacuum in between, which reduces heat transfer by conduction and convection. Over time, this design was adapted for everyday use to keep drinks hot or cold and became popular under the trade name thermos. Other names in the options, such as Tim Berners Lee and Ray Tomlinson, are associated with computer technology and the internet, not with vacuum flasks.

Step-by-Step Solution:

Verification / Alternative check:

Histories of cryogenics and everyday inventions state that Dewar created the vacuum flask so that he could store liquefied gases like oxygen and hydrogen. Later, commercial versions were sold for domestic use. Many sources actually refer to the vacuum flask as the Dewar flask in honour of its inventor. This consistent naming connection confirms that James Dewar is the right choice.

Why Other Options Are Wrong:

Ray Tomlinson is known for sending the first networked email and popularising the at symbol in email addresses.

Tim Berners-Lee created the World Wide Web, including the first web browser and server.

William Cullen performed early work on artificial refrigeration but did not design the modern vacuum flask used today.

William Thomson, known as Lord Kelvin, contributed to thermodynamics and temperature scales but did not invent the vacuum flask itself.

Common Pitfalls:

Students sometimes confuse different figures in the history of thermodynamics and refrigeration. While several scientists worked with low temperatures, the key point to remember is that the double walled vacuum flask is specifically attributed to James Dewar. Associating the word Dewar with vacuum flask helps prevent mixing up his name with other physicists working in similar fields.

Final Answer:

The thermos or vacuum flask was invented by James Dewar.