Science, Technology and Space

Overview

Science, Technology and Space appears about 3.5 times per paper across the last four AFCAT solved papers, placing it in the highest weight band of General Awareness.

Science questions in AFCAT stay deliberately applied. The paper is not testing a science graduate; it is testing whether a future officer can recognise the principle behind a stethoscope, name the vector of dengue, identify Aryabhata as India's first satellite, and tell isotopes from isobars. Almost every item fits one of six buckets — energy conversion, working principle, atomic or nuclear classification, biology and health, chemistry of common substances, or ISRO and Indian space technology.

The discipline of this topic is one-line ownership. For each device, one principle. For each disease, one pathogen and one vector. For each ISRO mission, one year and one significance. The chapter that follows builds those one-liners into tables you can revise the night before the exam.

Why AFCAT loves applied science

The General Awareness paper in AFCAT carries 25 questions out of 100. Of those, the science and technology cluster contributes roughly three to four questions in every paper — second only to defence awareness. The reason the Air Force Selection Board likes this cluster is simple. An officer-cadre candidate is expected to grasp the principles behind the equipment they will encounter, from the optics of a periscope to the working of a sonar, from the energy chain in a battery to the basic physics of supersonic flight. The questions are therefore framed around devices, classifications and named missions rather than equations.

Three patterns repeat across recent papers. First, an applied-physics item that names a device and asks for the underlying principle or the input-output energy chain. Second, a biology item that names a disease and asks for the pathogen, vector or vitamin. Third, a space item that names an ISRO mission, an Indian launch vehicle or a launch site. Knowing this distribution lets you map every science question to one of three quick lookup tables instead of solving from first principles.

Energy conversions in everyday devices

Every device on this list converts one form of energy into another. AFCAT typically gives you the device and asks for the conversion, or gives the conversion and asks for the device. Memorise both directions.

Two confusables to lock down. A dynamo converts mechanical to electrical energy; an electric motor does the reverse. A microphone converts sound to electrical signal; a loudspeaker reverses the chain. AFCAT tests the pairing.

Working principles of common devices

The shortcut for option-elimination is to ask which area of physics the device belongs to. Anything underwater is sonar and waves. Anything moving fluid is Pascal or Archimedes. Anything rotating fast is centrifugation. Anything with two coils is induction. Anything with light bending inside glass is total internal reflection.

Atomic and nuclear basics

The atom has a positively charged nucleus of protons and neutrons, with electrons in shells outside. The atomic number Z equals the number of protons. The mass number A equals protons plus neutrons. Almost every classification question in AFCAT uses these two numbers.

Fission and fusion are the two ways a nucleus releases energy.

• Nuclear fission: A heavy nucleus, typically Uranium-235 or Plutonium-239, splits into two lighter nuclei when struck by a slow neutron, releasing energy and more neutrons. This drives nuclear reactors and atomic bombs.
• Nuclear fusion: Light nuclei such as deuterium and tritium combine into a heavier nucleus, releasing far more energy than fission. Fusion powers the Sun and stars and is the principle behind the hydrogen bomb.
• Half-life: The time taken for half the atoms of a radioactive sample to decay. Each radioactive isotope has its own characteristic half-life — minutes for some, billions of years for Uranium-238.
• Radioactive elements: Uranium, Thorium, Radium, Polonium, Plutonium. Radioactivity was discovered by Henri Becquerel; Marie and Pierre Curie isolated radium and polonium.
• Bohr model: Electrons orbit the nucleus in fixed circular shells of definite energy. An electron emits or absorbs a photon when it jumps between shells. This explains the line spectrum of hydrogen.

Forces, motion and Newton's laws

Newton's three laws are the spine of mechanics and appear in AFCAT as one-line identification.

• First law (inertia): A body continues in its state of rest or uniform motion in a straight line unless acted upon by a net external force. Seat-belts and the lurch you feel when a bus brakes are everyday examples.
• Second law: Force equals mass into acceleration (F = ma). The rate of change of momentum equals the applied force.
• Third law: To every action there is an equal and opposite reaction. Rocket propulsion, recoil of a gun and swimming all illustrate it.

Other building blocks worth a line each.

• Momentum: Mass into velocity. Conserved in an isolated system — basis of rocket flight.
• Centripetal force: The inward force needed to keep a body moving in a circle. Loss of grip on a curve is a centripetal failure.
• Gravitational force: Every mass attracts every other mass. The acceleration due to gravity on Earth is about 9.8 m/s².
• Friction: Opposes relative motion between surfaces. Useful when walking, harmful in machine parts.
• Work, energy, power: Work is force into displacement; energy is the capacity to do work; power is the rate of doing work, measured in watts.

Light and optics

Light travels in straight lines and behaves as a wave. AFCAT asks about reflection, refraction, dispersion and instruments.

• Reflection: Angle of incidence equals angle of reflection. Plane mirrors form virtual, erect images of the same size.
• Refraction: Light bends when it passes from one medium into another of different density. A pencil in a glass of water looks bent because of refraction.
• Dispersion: White light splits into its seven constituent colours when it passes through a prism. The sequence VIBGYOR — violet, indigo, blue, green, yellow, orange, red — runs from highest to lowest refraction. Rainbow formation combines dispersion, refraction and internal reflection inside water droplets.
• Total internal reflection: When light travels from a denser to a rarer medium beyond the critical angle, it reflects entirely back. This is the principle of optical fibres and the mirage on a hot road.
• Lenses: Convex lenses converge light and are used in magnifying glasses, cameras and the human eye. Concave lenses diverge light and correct short-sightedness (myopia). Long-sightedness (hypermetropia) is corrected by convex lenses.
• Instruments: A microscope uses two convex lenses to magnify near objects. An astronomical telescope uses an objective of long focal length and an eyepiece of short focal length to view distant objects.

Sound and the speed of aircraft

Sound is a longitudinal mechanical wave that needs a medium. It travels fastest in solids, slower in liquids and slowest in gases. In dry air at twenty degrees Celsius the speed of sound is about 343 metres per second.

• Frequency: Number of vibrations per second, measured in hertz. Pitch depends on frequency.
• Wavelength: Distance between two successive crests. Speed equals frequency into wavelength.
• Amplitude: Maximum displacement from the mean position. Loudness depends on amplitude.
• Audible range: Human ear hears 20 hertz to 20,000 hertz. Below this is infrasonic, above is ultrasonic. Bats use ultrasonics for echolocation; sonar uses them underwater.
• Doppler effect: Apparent change in the observed frequency when source and observer move relative to each other. A passing siren rises in pitch as it approaches and drops as it recedes.
• Subsonic, transonic, supersonic and hypersonic: An aircraft is subsonic when slower than sound (Mach less than 1), transonic near Mach 1, supersonic between Mach 1 and Mach 5, and hypersonic above Mach 5. The Mach number is the ratio of the speed of an object to the speed of sound in the surrounding medium. Crossing Mach 1 produces the characteristic sonic boom.

Biology basics — cell, nutrition, vitamins

The cell is the basic structural and functional unit of life. Plant cells have a rigid cellulose cell wall, chloroplasts containing chlorophyll and a large central vacuole. Animal cells lack these but have centrioles. The nucleus carries genetic material as DNA organised into chromosomes; humans have 23 pairs.

• Photosynthesis: Plants synthesise glucose using carbon dioxide and water in the presence of sunlight and chlorophyll. The equation is 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂. Oxygen is released as a by-product.
• Respiration: Glucose is oxidised to release energy. C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP. ATP is the energy currency of the cell.
• Mitosis and meiosis: Mitosis produces two identical daughter cells for growth and repair. Meiosis halves the chromosome number to produce gametes for sexual reproduction.

Vitamins are organic compounds the body needs in small amounts but cannot make. Their deficiency causes characteristic diseases.

Human-body systems worth a one-line ownership.

• Circulatory: Heart pumps blood through arteries, veins and capillaries. Red blood cells carry oxygen using haemoglobin.
• Respiratory: Lungs exchange oxygen and carbon dioxide across alveoli.
• Digestive: Mouth, stomach, small intestine and large intestine. The liver is the largest gland; the pancreas secretes insulin.
• Excretory: Kidneys filter blood and produce urine.
• Nervous: Brain, spinal cord and nerves. The cerebrum controls thought; the cerebellum balances posture; the medulla runs involuntary actions.
• Endocrine: Pituitary is the master gland; thyroid produces thyroxine; pancreas produces insulin and glucagon.
• Immunity: Innate immunity is present from birth; acquired immunity develops after exposure or vaccination. Active immunity is produced by the body's own antibodies; passive immunity is borrowed, as in mother-to-baby antibodies through milk.

Diseases, pathogens and vectors

Memorise three pairings as a block — Anopheles with malaria, Aedes with dengue and chikungunya, Culex with filariasis and JE. AFCAT routinely tests one of them.

Chemistry essentials

Matter exists as solid, liquid or gas and is built from atoms. An element has only one kind of atom; a compound has two or more elements chemically combined.

• Periodic table: Elements are arranged in 18 vertical groups and 7 horizontal periods in order of atomic number. Properties repeat periodically.
• Alkali metals (Group 1): Lithium, sodium, potassium, rubidium, caesium, francium. Soft, low-density metals stored under kerosene because they react violently with water and air.
• Alkaline earth metals (Group 2): Beryllium, magnesium, calcium, strontium, barium, radium.
• Halogens (Group 17): Fluorine, chlorine, bromine, iodine, astatine. Highly reactive non-metals; chlorine is used to disinfect water.
• Noble gases (Group 18): Helium, neon, argon, krypton, xenon, radon. Chemically inert because of complete outer shells.

Acids, bases and salts.

• Acid: Releases hydrogen ions (H⁺) in water. Turns blue litmus red. Examples: hydrochloric acid, sulphuric acid, nitric acid, acetic acid (vinegar), citric acid.
• Base: Releases hydroxide ions (OH^-) in water. Turns red litmus blue. Examples: sodium hydroxide, potassium hydroxide, ammonium hydroxide, calcium hydroxide.
• Salt: Formed when an acid reacts with a base, accompanied by water. Common salt is sodium chloride.
• pH scale: Ranges from 0 to 14. Below 7 is acidic, 7 is neutral, above 7 is basic. Pure water is 7. Stomach juice is about 1.5.

Common compounds worth recognising.

• Baking soda — sodium bicarbonate, NaHCO₃.
• Washing soda — sodium carbonate decahydrate, Na₂CO₃.10H₂O.
• Bleaching powder — calcium oxychloride, CaOCl₂.
• Plaster of Paris — calcium sulphate hemihydrate.
• Quick lime — calcium oxide, CaO. Slaked lime is calcium hydroxide.
• Marble and chalk — calcium carbonate, CaCO₃.
• Hydrogen peroxide — H₂O₂, used as an antiseptic and bleach.

Ecosystem, biomagnification and energy transfer

An ecosystem is the interaction of living organisms with their non-living environment. Energy flows in one direction; matter cycles.

• Trophic levels: Producers (green plants) → primary consumers (herbivores) → secondary consumers (carnivores) → tertiary consumers (top carnivores) → decomposers (bacteria and fungi).
• 10% law of Lindeman: Only about 10 per cent of the energy at one trophic level is transferred to the next. The rest is lost as heat in respiration and metabolic activity. This is why food chains rarely exceed four or five levels.
• Biomagnification: The concentration of persistent pollutants such as DDT, mercury and polychlorinated biphenyls increases as you move up the food chain. Top predators carry the highest body burden.
• Biodiversity hotspots in India: The Western Ghats, the Eastern Himalayas, the Indo-Burma region and Sundaland. Hotspots have high endemism and significant habitat loss.
• Greenhouse gases: Carbon dioxide, methane, nitrous oxide, water vapour, ozone and chlorofluorocarbons. They trap outgoing infrared radiation and warm the atmosphere.
• Ozone layer: Found in the stratosphere; absorbs harmful ultraviolet radiation from the Sun. Depleted by chlorofluorocarbons. Protected under the Montreal Protocol.

ISRO and India's space programme

The Indian Space Research Organisation, founded in 1969 under the chairmanship of Dr Vikram Sarabhai, today runs one of the most cost-efficient space programmes in the world. AFCAT routinely asks one mission identification per paper.

Indian launch vehicles

• SLV-3: India's first satellite launch vehicle, retired in 1983. Launched Rohini RS-1 in 1980. Project director was Dr A.P.J. Abdul Kalam.
• ASLV: Augmented Satellite Launch Vehicle, used in the late 1980s and early 1990s.
• PSLV (Polar Satellite Launch Vehicle): ISRO's workhorse. Four-stage launcher used for sun-synchronous and polar orbits. Has launched Chandrayaan-1, Mangalyaan and most Indian remote-sensing satellites.
• GSLV (Geosynchronous Satellite Launch Vehicle): Three-stage launcher with a cryogenic upper stage; used for INSAT and GSAT communications satellites.
• LVM3 (formerly GSLV Mk III): India's heaviest operational launcher. Used for Chandrayaan-2, Chandrayaan-3 and the Gaganyaan crewed programme.
• SSLV (Small Satellite Launch Vehicle): A newer, lighter, on-demand launcher for small satellites up to about 500 kilograms.

Major ISRO and Indian science facilities

• Satish Dhawan Space Centre (SDSC SHAR): India's primary launch site, at Sriharikota in Andhra Pradesh.
• ISRO Headquarters: Antariksh Bhavan, Bengaluru, Karnataka.
• Vikram Sarabhai Space Centre (VSSC): Thiruvananthapuram, Kerala — leads launch-vehicle development.
• Liquid Propulsion Systems Centre (LPSC): Mahendragiri and Bengaluru — develops liquid and cryogenic engines.
• U R Rao Satellite Centre (URSC): Bengaluru — designs and builds satellites.
• Indian Institute of Remote Sensing (IIRS): Dehradun — training and applications.
• Master Control Facility (MCF): Hassan, Karnataka — tracks and operates geostationary satellites.
• Indian Deep Space Network: Byalalu near Bengaluru — supports interplanetary missions.
• Physical Research Laboratory (PRL): Ahmedabad — the cradle of Indian space science.

Indian defence-technology tie-ins

The Defence Research and Development Organisation (DRDO) sits at the centre of India's military technology. AFCAT occasionally tests its better-known systems.

• DRDO: Established in 1958, headquartered in New Delhi, with more than 50 laboratories across India. Develops missiles, radars, aircraft systems, electronic warfare suites and the indigenous combat aircraft programme.
• Integrated Guided Missile Development Programme: Conceived by Dr A.P.J. Abdul Kalam. Produced Prithvi (short-range surface-to-surface), Agni (long-range ballistic), Akash (surface-to-air), Trishul (short-range surface-to-air) and Nag (anti-tank).
• BrahMos: A supersonic cruise missile jointly developed by India and Russia, named after the Brahmaputra and Moskva rivers. Operational with all three services, including the Air Force's Su-30 MKI.
• Tejas (LCA): The Light Combat Aircraft developed by Hindustan Aeronautics Limited and the Aeronautical Development Agency. India's first indigenous single-engine multi-role fighter, inducted into the Indian Air Force.
• Astra: India's first indigenously developed beyond-visual-range air-to-air missile.
• Pinaka: A multi-barrel rocket launcher system developed by DRDO and produced by private partners.
• Indian Regional Navigation Satellite System (NavIC): A strategic asset providing position information independent of foreign systems such as GPS.

Worked AFCAT-style examples

Exam-day strategy

1. Build one revision sheet of energy conversions and one of working principles. Together they cover the bulk of applied-physics items in AFCAT.
2. Lock the four iso- terms and the fission-versus-fusion distinction in a single sitting. They reappear almost every paper.
3. Cover ISRO missions chronologically with one fact each — launcher, year and significance. Aryabhata, Rohini RS-1, Chandrayaan-1, Mangalyaan, Chandrayaan-3 and Aditya-L1 are the high-yield set.
4. For biology, prioritise the diseases-and-vectors table and the vitamins-and-deficiency table. The mosquito triad (Anopheles, Aedes, Culex) is asked routinely.
5. Treat Mach numbers, the Doppler effect and the audible range as Air-Force-relevant items worth a quick second read.
6. Aim for 35 to 45 seconds per science question. The cluster rewards recognition speed, not derivation.

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