Why do you experience an electric shock on touching a metal doorknob?
Science has answer to almost everything that happens in the universe. The occurrences could be as complex as the working of a celestial body or as simple as the way a simple foam is formed. Scientists have answers to the most ordinary things that we experience in our daily lives but fail to notice. Have you wondered why you face an electric shock while you touch a metal doorknob or why your breakfast cereals clump together? Come, let us learn more about some of common daily occurrences and the science behind them.
Electric shock from a doorknob
You must have faced this, right? Putting your hand on a metal doorknob suddenly gives you the feeling of an electric shock for a short while. Well, the culprit behind this is something called of static electricity. Wondering how? Let’s make it easy for you.
Usually, electricity always moves flowing through circuits. For example, when you plug in a lamp, it moves through the wire to the light. But in some cases, electricity has nowhere to go. This is called static electricity. But when is static electricity created? Everything around us is made of atoms, which comprise particles with positive charges or protons, particles with negative charges or electrons and those with no charge, neutrons. Static electricity is formed when there is a lack of balance between the positive and negative charges with electrons jumping from one object or person to another. On touching a doorknob, the extra electrons from your body want to find their way to the doorknob, which has a positive charge. The little shock that you experience is triggered by this process.
Clumping of breakfast cereals
You may have seen your morning cereal sticks to the sides of a milk bowl or forms clumps. Every wondered why? Scientists call this clumping phenomenon the 'Cheerio Effect,' which affects anything that floats, including bubbly soda bubbles! Lakshmi Narayanan Mahadevan, a mathematician from Harvard University, and Dominic Vella, professor of Applied Mathematics at Oxford, demonstrated that the shape of a liquid's surface causes the Cheerio Effect. Surface tension is defined as the tendency of liquid surfaces to compress into the smallest surface area possible when at rest. The centre of the bowl's milk surface slightly sinks due to surface tension and bends upward around the bowl's edge. Because of this, cereals close to the edge float upward along this curve, giving the impression that they are clinging to the edge!
Giant nuts sitting at the top
You have observed that Brazil nuts usually appear on top in a bowl of mixed nuts. It is referred to as the 'Brazil nut effect' and is one of the biggest puzzles in physics. Smaller objects tend to sink deeper into a pile over time. In contrast, larger ones tend to rise to the top with time among various things (nuts, sedimentary deposits, or other objects of varied sizes). The little things are slipping through the gaps. But the actual reason behind it is still being determined by scientists. The next time you eat nuts or granola or pick Doritos crumbs out of a bowl, try thinking about the physics at work!
Foam
We come across foam so frequently that only a few of us try to understand just how bizarre the substance is. Start by considering the following: Is whipped cream a gas, a liquid, or a solid? What if we told you it’s made of liquid and gas? According to the University of California Los Angeles physics professor Douglas Durian, foams generally comprise 95% gas and 5% liquid. These combine to give them solid-like characteristics. The gas in foam separates the liquid to create a network of tiny bubbles, and if the liquid walls of the bubbles are solid enough, the foam can occasionally maintain its shape. However, there is no formula for calculating the precise rigidity of a foam based on the size of its bubbles or the volume of liquid it contains. According to Durian, 'The mechanics of foam is poorly known.'