JSSC JE key terms

The principle that electrons and other particles show both wave and particle behaviour. De Broglie linked momentum to wavelength, and the photoelectric effect demonstrates particle-like photons, a standard General Science topic.

Emission of electrons from a metal surface when light of sufficient frequency strikes it. It proved light carries energy in discrete quanta and cannot be explained by classical wave theory alone.

The introductory statement of the Indian Constitution declaring the source of authority as the people and listing ideals such as justice, liberty, equality and fraternity. It is not enforceable but guides interpretation.

Guidelines in Part IV of the Indian Constitution directing state policy towards social and economic welfare. They are non-justiciable, meaning courts cannot enforce them, yet they shape legislation and governance.

Eleven obligations listed in Article 51A of the Indian Constitution, added by the 42nd Amendment, asking citizens to respect the Constitution, protect the environment and uphold public property and national unity.

A seasonal reversal of prevailing winds that brings heavy rainfall to India, driven by differential heating of land and sea and the northward shift of the ITCZ. The southwest monsoon delivers most annual precipitation.

A dry region on the leeward side of a mountain range, where descending air has already lost moisture. In India this explains the low rainfall of the Deccan interior behind the Western Ghats.

The interest rate at which the Reserve Bank of India lends short-term funds to commercial banks against securities. Raising it curbs inflation by making credit costlier; lowering it stimulates borrowing and growth.

The share of net demand and time liabilities that banks must hold as cash with the Reserve Bank of India. It earns no interest, so a higher ratio reduces lendable funds and tightens money supply.

A sustained rise in the general price level, reducing the purchasing power of money. It is commonly measured in India by the Consumer Price Index and Wholesale Price Index.

A ratio compares two quantities of the same kind by division, while a proportion states that two ratios are equal. Cross-multiplication solves proportions, a frequent shortcut in aptitude problems.

A fraction expressed with denominator 100, used to compare quantities on a common scale. Converting between fractions, decimals and percentages speeds up profit, loss and interest calculations.

Interest calculated on both the original principal and previously accumulated interest, so the amount grows geometrically. The formula is A = P(1 + r/n)^(nt) for n compounding periods per year.

Interest computed only on the original principal for the whole period, using SI = PRT/100. It grows linearly with time, unlike compound interest which grows exponentially.

The relation distance equals speed multiplied by time. Converting km/h to m/s by multiplying by 5/18 allows quick solution of train-crossing and relative-motion problems.

A form of deductive reasoning with two premises and a conclusion, tested through Venn diagrams. A conclusion is valid only if it follows necessarily from every possible arrangement of the premises.

A reasoning item asking for a pair of items related in the same way as a given pair, such as part to whole or cause to effect. Identifying the exact relationship is essential before choosing an option.

Finding the missing term in a sequence of numbers, letters or figures by detecting the underlying pattern. Differences, ratios, squares and alternating operations are common rules in such questions.

A reasoning topic where words are replaced by codes according to a fixed rule, and the candidate must decode or encode a new word. Letter shifts and positional values are usual keys.

Internal resistance force per unit area developed within a material under load, measured in newtons per square millimetre. Normal stress acts perpendicular to a section, while shear stress acts parallel to it.

The deformation of a body expressed as change in length divided by original length, a dimensionless quantity. It may be longitudinal, lateral or volumetric depending on the direction of measurement.

The ratio of normal stress to longitudinal strain within the elastic limit, denoted E. A high value indicates a stiff material that resists stretching, such as steel compared with rubber.

The negative ratio of lateral strain to longitudinal strain when a material is stretched. Typical values for metals lie near 0.3, and it is used in stress analysis of loaded members.

The internal moment at a section of a beam that resists rotation caused by transverse loads. Its maximum value determines the required section modulus in beam design.

The internal force acting parallel to a cross-section of a beam, equal to the algebraic sum of transverse loads on one side of the section. Its diagram helps locate points of maximum bending moment.

The ratio of a section's moment of inertia to the distance to its extreme fibre, denoted Z. Bending stress equals bending moment divided by section modulus.

The fraction of a soil's void volume filled with water, expressed as a percentage. At full saturation all voids contain water, and the soil behaves as a two-phase system.

The ratio of the volume of voids to the volume of solids in a soil mass, denoted e. It directly influences compressibility, permeability and shear strength of the soil.

The moisture content at which soil passes from a plastic to a liquid state, found by the Casagrande apparatus. Along with plastic limit it defines the plasticity index used in soil classification.

Biochemical Oxygen Demand: the oxygen consumed by microorganisms to decompose organic matter in a water sample over five days at 20 degrees Celsius. It measures organic pollution strength of wastewater.

Chemical Oxygen Demand: the oxygen equivalent of organic matter oxidised by a strong chemical oxidant under acidic conditions. It is measured faster than BOD and includes non-biodegradable matter.

The surveying operation of determining the relative heights of points using a level instrument and staff. Differential levelling establishes reduced levels needed for construction and drainage design.

A permanently fixed point of known reduced level used as a reference for levelling and setting out works. Temporary benchmarks are established near a site for convenience during construction.

Energy cannot be created or destroyed, only converted between forms. For a closed system, heat supplied equals change in internal energy plus work done by the system.

Heat flows spontaneously from a hotter to a colder body, and no cyclic device can convert all heat input into work. It fixes the maximum efficiency of heat engines via the Carnot limit.

A property measuring the degree of disorder or unavailable energy in a system. It increases in every real irreversible process, giving the criterion for the direction of spontaneous change.

A thermodynamic property equal to internal energy plus the product of pressure and volume, denoted H. It represents heat transfer at constant pressure, as in boilers and heat exchangers.

A dimensionless ratio of inertial forces to viscous forces in fluid flow, Re = rho v D / mu. Low values indicate laminar flow and high values turbulent flow in pipes.

For steady, incompressible, frictionless flow along a streamline, pressure energy, kinetic energy and potential energy per unit weight sum to a constant. It underlies flow measurement by venturi and orifice meters.