Light, Sound and Waves

Early diffraction experiments

Stories from Physics for 11-14 14-16 IOP RESOURCES

One of the earliest reports of diffraction used a feather as a grating. In a 1673 letter, James Gregory wrote to John Collins who acted as ‘post office’ to disseminate information in the scientific community:

“If ye think fit, ye may signify to Mr Newton a small experiment, which (if he know it not already) may be worthy of his consideration. Let in the Sun’s light by a small hole to a darkened house, and at the hole place a feather, (the more delicate and white the better for this purpose) and it shall direct to a white wall or paper opposite to it a number of small circles and ovals, (if I mistake them not) whereof one is somewhat white, (to wit, the middle, which is opposite to the Sun) and all the rest severally coloured. I would gladly hear his thoughts of it.”


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