UPSC Civil Services GK Questions 2026

In myopia the eyeball is too long or the lens of the eye too strongly converging, so rays from a distant object meet in front of the retina and the person cannot see far objects clearly.

An optical fibre is a thin thread of glass or plastic with a core of higher refractive index surrounded by a cladding of lower refractive index.

On a hot day the air touching the road is heated and becomes rarer than the cooler air above it.

The power of a lens is the reciprocal of its focal length expressed in metres, that is P equals 1 divided by f. Fifty centimetres is 0.5 metre, and the reciprocal of 0.5 is 2, so the power is two dioptres.

A convex mirror curves outward and spreads the light that falls on it, so it always forms a virtual, erect and diminished image, whatever the distance of the object.

Rays reflected from a plane mirror diverge and only appear to come from a point behind the mirror, so the image cannot be caught on a screen and is virtual.

Newton passed a narrow beam of sunlight through a glass prism in a darkened room and obtained a band of seven colours on the wall, which he named the spectrum.

By the sign convention the focal length of a concave lens is negative, so f is minus 15 centimetres, and the object distance measured against the direction of the incident light is minus 30 centimetres.

A denser medium has a higher refractive index, and the refractive index is the speed of light in vacuum divided by its speed in the medium, so light must travel more slowly inside it.

That is the consequence of ozone depletion, a separate problem caused by chlorofluorocarbons thinning the ozone layer in the stratosphere, and it is addressed by the Montreal Protocol.

The International Solar Alliance was launched jointly by India and France at the Paris climate conference in 2015 to promote solar energy among countries that lie largely between the tropics, and its secretariat was established at the campus of the National Institute of Solar Energy at Gwal Pahari in Gurugram…

The Montreal Protocol was agreed in 1987 under the Vienna Convention to phase out the substances that destroy stratospheric ozone, chiefly chlorofluorocarbons used in refrigeration, air conditioning and aerosol sprays.

The National Action Plan on Climate Change was released in 2008 and is built around eight national missions: the National Solar Mission, the National Mission for Enhanced Energy Efficiency, the National Mission on Sustainable Habitat, the National Water Mission, the National Mission for Sustaining the Himalayan Ecosystem, the National Mission…

Global warming potential measures how much heat a mass of a gas traps over a chosen period compared with the same mass of carbon dioxide, which is given the value one.

The Paris Agreement, adopted at the twenty-first Conference of the Parties in 2015 and in force from November 2016, commits its parties to holding the increase in the global average temperature to well below two degrees Celsius above pre-industrial levels and to pursuing efforts to limit the increase to one…

The Kyoto Protocol was adopted at the third Conference of the Parties held in the Japanese city of Kyoto in 1997, and it came into force in 2005 after enough countries had ratified it.

The United Nations Conference on Environment and Development, popularly called the Earth Summit, produced the Framework Convention on Climate Change along with the Convention on Biological Diversity and Agenda 21.

The two bodies set up the panel in 1988 so that governments would have a single authoritative summary of what science says about climate change.

Carbon dioxide is a greenhouse gas: it lets in the short wave radiation of the sun but absorbs a part of the long wave infrared radiation that the warmed earth sends back, and radiates it downwards again.

Sardar Vallabhbhai Patel was India's first Deputy Prime Minister and Home Minister, from 1947 until his death in 1950.