Static GK carries most of the General Knowledge marks in the defence exams, and science carries the largest share of it. In NDA & NA, Physics, Chemistry and General Science are about half of the 400 marks of Part B, and History, the freedom movement and Geography are about 20% each, as per the notice. In the CDS (II) 2026 General Knowledge paper, GK24 counted about 37 science questions, about 20 each on Polity and History, about 15 on Geography and environment and about 10 on the Economy; this count is guidance, not an official break-up. The Army's Agniveer CEE gives 15 of its 50 General Duty questions to General Knowledge and 15 to General Science, which covers cells, the human body, plants and animals and common epidemics. Its GK list names history, culture and geography of India and its neighbours, the Constitution, inventions and discoveries, books and authors, and the Indian Armed Forces. This page holds GK24's topic-wise GK notes and GK questions tagged for NDA, CDS and Agniveer, in English and Hindi: General Science, Indian History, Art and Culture, Indian Polity, Geography, Indian Economy and Static GK. Read one topic at a sitting, then solve its questions and the previous-year questions of your exam to see what stayed with you.
The essential condition for the action of a laser is
In ordinary matter most atoms sit in the lower energy level, so light passing through is absorbed more than it is amplified.
Read the full explanation →The expulsion of magnetic flux from the interior of a superconductor is known as
When a material becomes superconducting it pushes the magnetic field out of its interior and behaves as a perfect diamagnet, an effect reported by Meissner and Ochsenfeld in 1933; it is the reason a small magnet can be made to hover above a cooled superconductor, as in magnetic levitation demonstrations.
Read the full explanation →Superconductivity was discovered in 1911 in mercury cooled to about 4.2 kelvin by
The Dutch physicist Kamerlingh Onnes, who had already succeeded in liquefying helium, cooled mercury with it in 1911 and found that its electrical resistance disappeared completely below about 4.2 kelvin, the first observation of superconductivity.
Read the full explanation →The property of laser light by which all its waves are in the same phase is called
Coherence means that the waves in the beam keep a constant phase relationship, so crest marches with crest; this is a direct result of stimulated emission, since each new photon is emitted in phase with the photon that caused it, and it is what makes holography and interference work with…
Read the full explanation →The first working laser, a ruby laser, was built in 1960 by
Maiman built the first operating laser in 1960, using a rod of synthetic ruby, that is chromium ions in aluminium oxide, pumped by a flash lamp, and it emitted pulses of deep red light.
Read the full explanation →The word LASER is an abbreviation for
The device works by stimulated emission, in which a photon passing an excited atom makes it fall to a lower level and emit a second photon identical in frequency, phase and direction, so one photon becomes two and the light is amplified.
Read the full explanation →The minimum energy required to eject an electron from the surface of a metal is called its
The work function of a metal is the least energy needed to free an electron from its surface, and it is equal to Planck's constant multiplied by the threshold frequency of that metal; caesium and potassium have low work functions, which is why they respond to visible light.
Read the full explanation →The maximum kinetic energy of the photoelectrons emitted from a metal surface depends on
By Einstein's photoelectric equation, the photon gives energy equal to Planck's constant times the frequency, part of which is spent as the work function, so the maximum kinetic energy left with the electron rises with frequency and is independent of how bright the light is.
Read the full explanation →Albert Einstein was awarded the Nobel Prize in Physics for 1921 mainly for
The citation for the prize refers to his services to theoretical physics and especially to his discovery of the law of the photoelectric effect, the equation in which the energy of a photon equals the work function plus the maximum kinetic energy of the emitted electron.
Read the full explanation →The photoelectric effect was first observed by which scientist?
In 1887, while studying the sparks produced across a gap between two electrodes, Hertz noticed that the spark passed more easily when ultraviolet light fell on the electrodes, which was the first observation of the photoelectric effect; Hallwachs and Lenard then studied it systematically.
Read the full explanation →With reference to organic farming in India, consider the following statements :
1. 'The National Programme for Organic Production' (NPOP) is operated under the guidelines and directions of the Union Ministry of Rural Development.
2. 'The Agricultural and Processed Food Products Export Development Authority' (APEDA) functions as the Secretariat for the implementation of NPOP.
3. Sikkim has become India's first fully organic State.
Which of the statements given above is/are correct?
NPOP is run by the Ministry of Commerce and Industry, not Rural Development, while the statements about APEDA and Sikkim are correct.
Read the full explanation →Consider the following :
1. Birds
2. Dust blowing
3. Rain
4. Wind blowing
Which of the above spread plant diseases ?
Birds, blowing dust, rain and wind can all carry the agents of plant disease from one plant to another. Plant pathogens such as fungi, bacteria and viruses cannot move on their own over long distances, so they depend on carriers.
Read the full explanation →Which one of the following is not a feature of Indian federalism ?
Indian federation was not formed by States coming together under an agreement, which is why the Constitution calls India a 'Union of States'.
Read the full explanation →Consider the following statements :
1. The definition of "Critical Wildlife Habitat" is incorporated in the Forest Rights Act, 2006.
2. For the first time in India, Baigas have been given Habitat Rights.
3. Union Ministry of Environment, Forest and Climate Change officially decides and declares Habitat Rights for Primitive and Vulnerable Tribal Groups in any part of India.
Which of the statements given above is/are correct ?
The Forest Rights Act defines critical wildlife habitat, and the Baigas were the first community to receive habitat rights, but the Environment Ministry does not grant those rights.
Read the full explanation →Out of the following statements, choose the one that brings out the principle underlying the Cabinet form of Government :
The heart of Cabinet government is collective responsibility: the ministers stand or fall together before the elected House. Article 75(3) of the Constitution says the Council of Ministers shall be collectively responsible to the Lok Sabha, and Article 164(2) says the same for State ministers and the Legislative Assembly.
Read the full explanation →Which one of the following statements is not correct?
The truth is the reverse: hepatitis B has a safe, effective vaccine, while hepatitis C has none. The hepatitis B vaccine has been in use since the 1980s and is given to newborns in India under the Universal Immunisation Programme, with the first dose soon after birth.
Read the full explanation →Which of the following is geographically closest to Great Nicobar ?
Sumatra in Indonesia lies just across the sea to the south-east of Great Nicobar, the southernmost island of India.
Read the full explanation →What is Cas9 protein that is often mentioned in news?
Cas9 is the enzyme in the CRISPR-Cas9 system that cuts DNA at a chosen spot, which is why it is called molecular scissors.
Read the full explanation →Which of the following are envisaged by the Right against Exploitation in the Constitution of India ?
1. Prohibition of traffic in human beings and forced labour
2. Abolition of untouchability
3. Protection of the interests of minorities
4. Prohibition of employment of children in factories and mines
Select the correct answer using the code given below :
The Right against Exploitation is made up of Articles 23 and 24, which cover exactly items 1 and 4. Article 23 prohibits traffic in human beings, begar and other similar forms of forced labour, and Parliament has backed it with laws such as the Bonded Labour System (Abolition) Act, 1976.
Read the full explanation →With reference to India's satellite launch vehicles, consider the following statements :
1. PSLVs launch the satellites useful for Earth resources monitoring whereas GSLVs are designed mainly to launch communication satellites.
2. Satellites launched by PSLV appear to remain permanently fixed in the same position in the sky, as viewed from a particular location on Earth.
3. GSLV Mk III is a four-staged launch vehicle with the first and third stages using solid rocket motors; and the second and fourth stages using liquid rocket engines.
Which of the statements given above is/are correct ?
PSLV mainly carries Earth observation satellites to low orbits, GSLV was built for communication satellites, and the other two statements describe the rockets wrongly.
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