Author: karansinghbhardwaj
THE LEIDENFROST EFFECT
All of you must have noticed that when you start heating a hot plate and pour some water on it , it quickly evaporates. But after some time when the hot plate is extremely hot and you pour some water on it, water takes the form of small spherical shapes. But ever wondered why this happens? It is due to a phenomenon known as ‘The Leidenfrost Effect’ in which a liquid, in near contact with mass significantly hotter than the liquid’s boiling point, produces an insulating vapor layer keeping that liquid from boiling rapidly.
This effect is also responsible for the ability of liquid nitrogen to skitter across floors and even when you dip your hand in liquid nitrogen for a small period of time, no injuries or freezing of hand occurs.
This effect also protects the demonstrator when he dips a wet finger in molten lead, or blow out a mouthful of liquid nitrogen.
THE FLUX-PINNING EFFECT !!
Flux pinning is the phenomenon where a superconductor is pinned in space above a magnet. The act of magnetic penetration is what makes flux pinning possible. At higher temperatures the superconductor allows magnetic flux to enter in quantized packets. These sites of penetration are known as flux tubes. At very low temperatures as that at which liquid nitrogen is obtained the flux tubes are pinned in place and cannot move. This pinning is which holds the superconductor in place and allow it to levitate. This phenomenon is closely related to the ‘ Meissner Effect ‘, though with one crucial difference — the Meissner Effect shields the superconductor from all magnetic fields, causing repulsion, unlike the pinned state of the superconductor.
To understand better see the following video —
Why is glass transparent?
A common misconception about the opacity of objects is that people consider substances that are solid to be opaque and substances that are liquids and gases to be transparent and translucent.A common example being that of glass which is a super-cooled liquid.People think that due to high inter molecular spaces between liquids and gases,they allow light to pass right through the spaces between the atoms.Similarly for solids as the space between individual atoms is very low,photons strike the atoms and are reflected back,which is not in fact the case.
To know the reason behind it check out the video below:
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