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The International Day of Light, observed on 16 May, marks the anniversary of:
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Answer: Option A — The first successful operation of the laser (1960)
Detailed Solution
The International Day of Light is observed every year on 16 May, the anniversary of the first successful operation of the laser by the American physicist and engineer Theodore Maiman in 1960.
About the International Day of Light:
- It was proclaimed by UNESCO in November 2017 and was first celebrated on 16 May 2018.
- It follows the success of the International Year of Light and Light-based Technologies in 2015.
- It highlights the role of light in science, culture, art, education, sustainable development, medicine, communications and energy.
About the first laser:
- On 16 May 1960, Theodore Maiman, working at Hughes Research Laboratories in California, operated the first working laser, using a synthetic ruby crystal.
- "LASER" stands for "Light Amplification by Stimulated Emission of Radiation".
- The theory of stimulated emission had been proposed by Albert Einstein in 1917.
- Lasers are now used in surgery (for example, eye surgery), barcode scanners, optical fibre communication, printers, cutting and welding, measurement and entertainment.
Light-related facts:
- The speed of light in a vacuum is about 3 x 10^8 metres per second (299,792,458 m/s).
- Light shows both wave and particle (photon) nature.
Other important dates in the history of light:
- V. Raman discovered the Raman Effect (scattering of light) on 28 February 1928. National Science Day is celebrated on this date. He received the Nobel Prize in Physics in 1930.
- Thomas Edison demonstrated a practical incandescent light bulb in 1879.
- The Hubble Space Telescope was launched on 24 April 1990.
Indian connection:
Narinder Singh Kapany, an Indian-American physicist, is known as the "Father of Fibre Optics". He received the Padma Vibhushan posthumously in 2021.
Why not the other options?
- ✗The Raman Effect (28 February 1928) is marked on National Science Day.
- ✗Edison's practical light bulb was demonstrated in 1879.
- ✗The Hubble Space Telescope was launched in April 1990.
Quick tip
Remember: International Day of Light = 16 May (first laser by Theodore Maiman, 1960; UNESCO 2017, first observed 2018; International Year of Light was 2015); LASER = Light Amplification by Stimulated Emission of Radiation.
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Important Days & Dates — Preparation
This question tests your understanding of Important Days & Dates, a key topic in the General Knowledge section. The detailed solution above uses a step-by-step approach to show the reasoning, and where available, a shortcut that helps you solve similar questions in under 90 seconds during the actual exam.
This topic covers national and international days observed through the year, such as National Youth Day, World Environment Day and International Yoga Day, along with the themes announced for them and the events or people they commemorate. Questions ask for the date of a day, the day observed on a given date, or the person it honours (for example, National Sports Day on 29 August marks the birthday of Major Dhyan Chand). Revise days month by month in a calendar format. Themes change every year, so learn the current year's themes from current affairs. Practise the important days questions below, written in the style of the general awareness sections of exams such as SSC, banking, railways, CUET GAT, MAH CET and CLAT. Each question comes with a detailed explanation that adds related facts, so every question helps you revise more than one point.