Everyday explained: Why should we not use stainless steel utensils in a microwave?

While we are aware that stainless steel or any metal utensils in a microwave pose a hazard, not many of us are sure why. Here is the real reason.
We all know that stainless steel utensils, or metal objects in general, including cutlery, should never be placed inside a microwave oven while operational. Today’s everyday explained explores the reason behind the warning.
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How does a microwave oven work?
To understand why we should not be putting metal inside a microwave oven, we first need to know how the appliance works. Microwaves are a form of electromagnetic radiation, like radio waves, but with shorter wavelengths and higher frequencies.

According to Caroline A. Ross, a professor in the department of Materials Science and Engineering at the Massachusetts Institute of Technology (MIT), a microwave oven generates microwaves by a device called a magnetron, and they are made to pulse back and forth inside the appliance at a carefully calibrated frequency.
Microwaves bounce off the oven’s interior metal walls, can pass through paper, glass, and plastic, but they get absorbed by food. More specifically, the microwaves get absorbed by the food’s water content. The transfer of energy that takes place leads to the water molecules of food oscillating back and forth rapidly, which creates heat and warms up the food. It can also cook the food from the inside out, the outside in, or uniformly, depending on where the water lies.
Why we should not put stainless steel or metal inside a microwave
In the words of Professor Ross, it is “counterproductive to put something metallic inside your microwave oven if you want to heat it up.” She explained that a metal object placed inside the microwave oven deflects the microwaves away from the food.
The deflected electromagnetic waves jump around erratically inside the appliance, which can end up damaging the interior of the oven. In fact, metal is so good at reflecting microwave radiation that the window built into the front of microwave ovens contains a fine metallic mesh that we can see through, but from which microwaves cannot escape.
In some situations, metal placed inside a microwave can become very hot. The oscillation of the microwaves can also produce a concentrated electric field at the corners or the edge of a metallic object, and thereby ionise the surrounding air. When the electric fields are strong enough, they can cause arcing, or the formation of visible sparks. This can damage the internal components of the appliance and become a larger safety hazard in general.
ABOUT THE AUTHORDebapriya BhattacharyaDebapriya Bhattacharya is a Content Producer at Hindustan Times. He started his career in 2022, working in newsrooms in beats like education, US news, trending stories, and entertainment. In his new role in the lifestyle desk, he seeks to deliver a balanced blend of research-driven reporting and creative storytelling from health and recipes to art and culture. Science, philosophy, food and pop culture are what pump his veins and help bring heart to his stories. Debapriya tries to see out subjects that will allow him and readers to explore new frontiers and improve the quality of life for all. The explorations can be both external and internal, as thoughts seek to be as chaotic as the greater universe. As a citizen of the world, Debapriya has been fascinated by the lives of people across the globe throughout time. His curiosity leads him to explore new linguistic and cultural landscapes to broaden his horizons and deepen his understanding of global narratives. Beyond the newsroom, Debapriya loves to participate in debate and theatre, spaces that he considers to be holy grounds for nuance and self-expression. A graduate from Ashutosh College, University of Calcutta, Debapriya completed his Master's degree from the same university in 2022. An ambiverted bibliophile, he loves his solitude as much as he adores stimulating conversations. And despite his reverence for tech, libraries continue to be his favourite place for research.Read More

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